今天小编就给大家整理了英语语法if的用法解释（共含6篇），希望对大家的工作和学习有所帮助，欢迎阅读!同时，但愿您也能像本文投稿人“做狗自由”一样，积极向本站投稿分享好文章。
as if 从句的语气及时态
1. as if 从句用陈述语气的情况。 当说话者认为句子所述的是真实的或极有可能发生或存在的事实时。
如：
It sounds as if it is raining.
听起来像是在下雨。
He talks as if he is drunk.
从他谈话的样子来看他是醉了。
2.as if 从句用虚拟语气的情况。 当说话人认为句子所述的是不真实的或极少有可能发生或存在的情况时。从句虚拟语气动词时态的形式如下：
(1)如果从句表示与现在事实相反，谓语动词用一般过去时。
如：
You look as if you didn’ t care.
你看上去好像并不在乎。
He talks as if he knew where she was.
他说话的样子，好像他知道她在哪里似的。
(2)从句表示与过去事实相反，谓语动词用“had+过去分词”。
如：
He talks about Rome as if he had been there before.
他说起罗马来好像他以前去过罗马似的。
The girl listened as if she had been turned to stone.
那女孩倾听着，一动也不动，像已经变成了石头似的。
(3)从句表示与将来事实相反，谓语动词用“would/could/might+动词原形”。
如：
He opened his mouth as if he would say something.
他张开嘴好像要说什么。
It looks as if it might snow.
看来好像要下雪了。
(4)as if 后面可以接陈述语气和虚拟语气，如果句子的情况是真实的，那么只要保持时态一致即可，如果后面接的并非真实情况，则要按照虚拟语气规则把句子形式改变(简单说就是事态倒退原则)。
举例：
it seems as if it is raining。外面看起来象是下雨了。(陈述)
it seems as it it were raining。外面看起来好像下雨一样。(虚拟，其实并没有下雨)
一、as if 从句的作用
1. 在look, seem 等系动词后引导表语从句。
如：
She looks as if she were ten years younger.
她看起来好像年轻了十岁。
It seems as if our team is going to win.
看来我们队要胜了。
2. 引导方式状语从句。
如：
She loves the boy as if she were his mother.
她爱这男孩，就好像她是他的母亲一样。
The child talked to us as if he were a grown?up.
那孩子跟我们谈起话来，像个成年人似的。
二、as if 还可用于省略句中如果as if 引导的从句是“主语+系动词”结构，可省略主语和系动词，这样as if 后就只剩下名词、不定式、形容词(短语)、介词短语或分词。
如：
He acts as if (he was) a fool.
他做事像个傻子。
Tom raised his hands as if (he was going) to say something. 汤姆举起手好像要说什么。
She left the room hurriedly as if (she was)angry.
她匆忙离开房间好像生气的样子。
五、It 用作形式宾语用来替代作宾语的从句、动词不定式、动名词，而把真正作宾语的从句、动词不定式、动名词置于句尾。
It 作形式宾语的常见句型：
1. verb+ it+ adj./noun (for/of) to do/clause (verb=think, believe, suppose, consider, feel, make, keep…)例I think it hard for you to do the task on your own./I think it hard that you'll do the task on your own.
2. verb+it+adj./noun (one's) doing (adj.=useless/worth/worthwhile)(noun=no use/no good/worth one's while/a waste of time/money/energy/words) (verb=think, believe, suppose, consider, feel, make, keep…)例I'll make it worth your while telling me about his secret.
3. verb+it+ important/unimportant/necessary/unnecessary/natural/essential that … (should)…verb+it+of much/great/no/little importance that…(should)…(verb=think, believe, suppose, consider, feel, make, keep…)例I think it important that you (should) attendthe conference.
4. verb + it+ as+ noun/adj.+ clause (verb=accept, regard, take, see, view)例The lecturer takes it as encouraging when so many students attend his lecture.
5. v. +it + prep. + that…owe it to sb. that…把…归功于…leave it to sb that…把…留给某人去做take it for granted that …想当然keep it in mind that…例Don't bother to arrange anything. Just leave it to me to sort out.
6. It用在不能直接跟宾语从句的动词后面，尤其是表示好恶的动词后，enjoy, like, love, dislike, resent, hate, don't mind, be fond of, feel like, see to 宾语从句紧跟it之后例I hate it you can swim so well and I can't.
7. It用在不能直接跟宾语从句的介词后面，宾语从句紧跟it之后(except that例外)例I'm for it that you will follow their advice.
英语语法：被动语态用法大全
概念
语态(Voice)是动词的一种形式，用以表示主语和谓语之间的关系。
英语的语态包括两种形式：
主动语态(active voice)和被动语态(passive voice)。主动语态表示主语是动作的执行者，被动语态表示主语是动作的承受者。
被动语态是动词的一种特殊形式，一般来说，只有需要动作对象的及物动词才有被动语态。主动语态表示主语是动作的执行者。巧记为：主动、主动、主去动。
Many people speak English.谓语：speak的动作是由主语many people来执行的。被动语态表示主语是动作的承受者，即行为动作的对象。
巧记为：被动、被动、主被动。English is spoken by many people.主语English是动词speak的承受者。He opened the door.他开了门。(主动句)The door was opened.门被开了。(被动句)
构成
His bicycle was stolen.The building has been built in .通过上面的例句，可以看出，“被动语态”的构成是：be + 过去分词 ( + by + 动作执行者)
形式
被动语态由助动词be加及物动词的过去分词构成，强调动作是由什么人或什么东西而发出时，常用介词“by +行为发出者”，即be+done+by+行为发出者。
被动语态可用于各种时态，通过助动词be的变化来表示：
1、一般现在时的被动语态. am / is / are + 动词的过去分词Our classroom is cleaned every day.This car is made in China.
2、一般过去式的被动语态: was / were + 动词的过去分词His desk was cleaned just now.The station was built in 1928.
3、现在进行时的被动语态: am / is / are + being + 动词的过去分词A new factory is being built in our city now.Some trees are being cut down in the park.
4、过去进行时的被动语态: was / were + being + 动词的过去分词A new factory was being built in our city at that time.Some babies were being looked after by Miss Chen last year.
5、一般将来时的被动语态:(A) will / shall + be + 动词的过去分词(B) am / is / are + going to be +动词的过去分词.Some new factories will be built in our city this year.Your watch is going to be mended in an hour.
6、过去将来时的被动语态:(1)would / should + be + 动词的过去分词(2)was / were +going to be + 动词的过去分词.She said that some new factories would be built soon in our city.He thought that your watch was going to be mended after an hour.
7、现在完成时的被动语态:have / has + been + 动词的过去分词Some new factories have been built in the city since last year.Your watch has been mended already.
8、过去完成时的被动语态:had + been + 动词的过去分词He said that some new factories had been built in the city.I didn’t know that my watch had been mended .
9、含情态动词的被动式：can/may/must + be + done(1)You must hand in your homework after class.Your homework must be handed in after class.(2)He can write a letter with the computer.A letter can be written with the computer by him.
| 初中英语八大时态 | ||
| 一般现在时 | 一般过去时 | 一般将来时 |
| 现在进行时 | 过去进行时 | 过去将来时 |
| 现在完成时 | 过去进行时 |
运用
第一种情况：不知道动作的执行者，就是不知道谁干的Dan's bike was stolen last week. 丹的自行车上周被偷了。My windows were broken yesterday. 我的窗户昨天被打烂了。
第二种情况：没有必要交代动作的执行者，就是说：不用说出来大家也知道谁干的Rice is also grown in North China. 华北地区也种水稻。A new railway station will be built next year. 明年要建一座新的火车站。
第三种：为了强调动作的承受者，这里我们比较一下主动和被动：Prisoners of War built the bridge. 战俘修建了这座桥。此句的主句是 Prisoners of War，是来回答 Who built the bridge? 这个问句，所以此句强调的是动作的执行者---战俘，交代战俘做了什么事。变被动之后：The bridge was built by Prisoners of War.这座桥是被战俘修建的。这样说的话，主语变成了“the bridge”---这座桥，此句是回答 What was built? 所以此句是强调“什么被建造”即强调动作的承受者。又如：The book was written by Shi Naian. 这本书是施耐庵写的。以上是被动语态使用的三种情况或者说时机，第三种虽然强调动作的承受者，但一般也要交代动作的执行者，用 by + 执行者 来表达。
主动语态变成被动语态
1、从句子意义上说，就是重新找出“什么事物”是“被完成”的。
主动语态：人们说英语。People speak English in many countries.被动语态：英语被说。English is spoken in many countries..主动语态：我们造这座桥。We built this bridge last year.被动语态：这座桥被建造。This bridge was built last year.2、从语法的角度说，把原句的宾语改成主语。主动语态：小王邀请你(宾语)Xiao Liu has invited you to a lunch party.被动语态：你(宾语)被邀请。You has been invited to a lunch party by Xiao Wang.主动语态：你不准带走杂志(宾语)You must not take these magazines out of the reading-room.被动语态：杂志(宾语)不准被带走.These magazines must not be taken out of the reading room.主动语态：他们授给他(宾语)一枚奖章(宾语).They gave him a medal for his wonderful work.被动语态：他(宾语)被授予一枚奖章.He was given a medal for his wonderful work.被动语态：一枚奖章(宾语)被授给了他.A medal was given to him for his wonderful work.语态转换时所注意的问题
1. 把主动语态变为被动语态，其谓语动词的时态要与原句时态保持一致，其谓语动词的数要与新主语保持一致。We have bought a new computer.A new computer has been bought.A new computer have been bought. (错误)
2. 含有双宾语的主动句变被动句时，可分别将其中的一个宾语变为主语，另一个不动，一般变间接宾语为主语时比较多My uncle gave me a present on my birthday.I was given a present on my birthday.如果把直接宾语(指物)改为主语，则在间接宾语(指人)前加适当的介词，如上句还可以说：A present was given to me yesterday.
注意：1.一般在下列动词后，常在间接宾语前用介词 to，如：bring, give, hand, lend, offer, pass, pay, promise, sell, show, take, teach, tell 等。(1) The book was showed to the class.(2) My bike was lent to her.
2.一般在下列动词后，间接宾语前用介词 for, 如：build, buy, cook, cut, choose, do, fetch, find, fix, get, keep, make, order, paint, play, sing 等。(1) A new skirt was made for me.(2) The meat was cooked for us.(3) Some country music was played for us.
3. 由动词+ 介词或副词构成的短语动词，要把它们作为整体看，即把它们看成一个及物动词，介词或副词不可拆开或漏掉。这类动词有：不及物动词+ 介词，如: agree to, ask for, laugh at, operated on, listen to, look after, think of, talk about 等。The patient is being operated on. The problem is solved. It needn't be talked about.及物动词+ 副词：如：bring about, carry out, find out, give up, hand in, make out, pass on, point out, put away, put off, think over, turn down, work out, turn out 等。His request was turned down.The sports meet will be put off because of the bad weather4. 带复合宾语(宾语+ 宾补)的动词改为被动语态时，一般把主动结构中的宾语改为主语，而宾语补足语保留在谓语动词后面。
(1) We always keep the classroom clean.→The classroom is always kept clean.
(2) She told us to follow her instructions.→We were told to follow her instructions.注意：在see, watch, hear, notice, listen to, look at, make, feel等动词后作宾语补足语的动词不定式都不带 to，但改成被动语态后都带to，这时不定式为主语补足语，也就是说不定式作主语补足语不存在省略to 的问题。We often hear him play the guitar.→He is often heard to play the guitar.
5. 当主动句的主语是nobody, no one等含有否定意义的不定代词时，被动句中将其变为anybody,作by的宾语，并将谓语动词变为否定的被动语态。Nobody can answer this question.误：The question can be answered by nobody.正：The question can not be answered by anybody.
6. 当否定句中的宾语是anything, anybody, anyone等不定代词时，在被动句中应将其分别变为nothing, nobody, no one作主语，并将谓语动词变为肯定的被动语态。They haven't done anything to make the river clean.误：Anything hasn't been done to make the river clean.正：Nothing has been done to make the river clean.
7. 以who为主语开头的疑问句，变被动时，用by whom放在句首：Who wrote the story?误：Who was the story written?正：By whom was the story written?
8. 有些动词既是及物又是不及物，当它们和well, badly, easily等副词连用时，表示主语内在品质或性能，是不及物动词，用主动表示被动，这时不用被动语态，常见的有：write, read, clean, sell, wash, cook 等。(1)The cloth washes easily. 这布很好洗。(2)The new product sells well. 这新产品很畅销。对比：The books sell well. (主动句)The books were sold out. (被动句)The meat didn’t cook well. (主动句)The meat was cooked for a long time. (被动句)
9. 下列情况主动句不能改为被动句：第一，感官系动词一般用主动形式表示被动意义，如：feel，look, seem, taste, sound, remain等。(1)— Do you like the material?— Yes, it feels very soft.误：It is felt very soft.(2)The food tastes delicious.误：The food is tasted delicious.(3)The pop music sounds beautiful.误：The pop music is sounded beautiful.第二，谓语是及物动词leave, enter, reach, suit, have, benefit, lack, own等。He entered the room and got his book.误：The room was entered and his book was got.She had her hand burned.误：Her hand was had burned.第三，一些不及物动词短语没有被动语态：take place, break out, belong to, lose heart, consist of, add up to等。The fire broke out in the capital building.误：The fire was broke out in the capital building.第四，不及物动词没有被动语态，如：rise, happen, succeed, remain, lie等。When we got to the top of the mountain, the sun had already risen.误：The sun had already been risen.After the earthquake, few houses remained.误：After the earthquake, few houses were remained.第五，宾语是反身代词，相互代词，同源宾语，不定式，v-ing形式及抽象名词等，不能变为被动句子的主语，如：I taught myself English.误：Myself was taught English.We love each other.误：Each other is loved.
初中教材中与被动语态相关的句型
1.be covered with被……覆盖
2.be made of由……制作(发生物理变化)be made from由……制作(发生化学变化)be made in由(某地)制造be made by被(某人)制造3.be used for被用来……be used as被当作(作为)……来使用be used to do sth.被用来做某事4.It is said that...据说……It is hoped that...希望……It is well known that...众所周知……例如：
几种特殊的被动语态
1.带不定式的被动语态。The child is sure to be punished for that. 那个孩子肯定会因为那件事受罚的。2. 带介词的动词短语的被动语态。Such a thing has never been heard of. 这件事前所未闻。3. 带副词的动词短语的被动语态。The radio has just been turned off. 收音机刚刚被关上。4. 当sell, wash, clean, run, ride, wear, write等动词若有状语well, easily, badly来修饰时，用主动形式表达被动意义。The pen writes well. 这枝钢笔写字流畅。The book sells well. 这本书很畅销。
形式为主动，意义为被动。(中考难点)
1.由少数及物动词转化来的不及物动词(sell, clean, wash, cut, drive, wear, write等)，当句子的主语为物时，可用主动形式表被动意义。The car drives well.The cloth washes easily.2.在be worth doing, need doing中，主语是物，doing表示被动意义。The book is worth reading.The tree needs watering.3.形容词 cheap, dangerous, important, comfortable, interesting等接不定式做状语时，不定式的主动形式表被动意义。The old lady is easy to get along with.The question is difficult to answer.4.感官动词look, sound, taste, smell, feel等，主动语态表被动意义。You look unhappy.The cake tastes delicious.
口诀
一般现在时、一般过去时用be +及物动词的.过去分词，be有人称、时、数变。
完成时态have(has)done，被动将been加中间。一般将来shall(will)do，被动变do为be done。将来进行无被动，shall(will)be doing。现在完成时，被动 have(has)been done。现、过进行be doing，被动be加being done。情、助、有、是妥安排，一律随新主语变。否定助后加not，疑问一助置主前。主语恰是疑问词，直陈语序主在前。一般情助加be done，双宾多将间宾变。复合宾语宾变主，宾补、主补相应变。
关于小升初英语语法推荐：with用法
1. 带着，牵着…… (表动作特征)。如：
Run with the kite like this.
2. 附加、附带着……(表事物特征)。如：
A glass of apple juice, two glasses of coke, two hamburgers with potato chips, rice and fish.
3. 和…… (某人)一起。
a. 跟某人一起(居住、吃、喝、玩、交谈……) 。如：
Now I am in China with my parents.
Sometimes we go out to eat with our friends.
He / She's talking with a friend.
b. 跟go, come 连用，有 “加入”到某方的意思。如：
Do you want to come with me?
4. 和play一起构成短语动词play
with 意为“玩耍……，玩弄……”如：
Two boys are playing with their yo-yos.
5. 与help 一起构成 help…with…句式，意为“帮助 (某人) 做 (某事)”。如：
On Monday and Wednesday, he helps his friends with their English.
6. 表示面部神情，有“含着……，带着……”如：
“I'm late for school,” said Sun Yang, with tears in his eyes.
7. 表示 “用……”如：
You play it with your feet.
What do the farmers do with your machines?
8. 表示 “对……， 关于……”。如：
What's wrong with it?
There's something wrong with my computer.
一、介词to的常见用法
1.动词+to
a)动词+ to
adjust to适应，
attend to处理;照料，
agree to赞同，
amount to加起来达…，
belong to属于，
come to达到，
drink to为…干杯，
get to到达，
happen to发生在某人身上，
hold to紧握，
lead to通向，
listen to听，
occur to想起，
object to反对，
point to指向，
respond to回答，
refer to参考;指的是…;涉及，
reply to回答，
see to负责，
stick to坚持，
turn to求助，
write to给某人写信。
b)动词(+sth.)+to+sb.
announce to通知某人， describe to向某人描述， explain to向某人解释， express to对某人表达， mention to提及， nod to向某人点头， report to报告， say to告知， shout to对某人大叫， suggest to对某人提建议，speak to与某人交谈， talk to跟某人谈话， whisper to和某人低声耳语。
c)动词+sth./sb.+ to +sth./sb.
add to增加， compare to比作， carry to运送至， devote to致力于，introduce to介绍给， invite to邀请参加， join to连接到， leave to委托给，reduce to下降至， sentence to判处， take to带到。
2. be +形容词/过去分词+ to
be alive to觉察;晓得，
be attentive to注意;留心，
be awake to知晓，
be blind to缺乏眼光，
be close to紧挨着，
be common to对某人来说很普通，
be contrary to违反;反对，
be devoted to致力，
be deaf to不愿意听，
be equal to有…的力量，
be exposed to暴露;遭受，
be fair to对…公平，
be familiar to对某人来说熟悉，
be grateful to对某人心存感激，
be good to对…有好处，
be harmful to对…有危害，
be important to对…重要，
be kind to友好对待，
be known to周知于，
be married to嫁给，
be moved to转移到，
be near to靠近，
be necessary to对…有必要，
be opposite to在对面，
be opposed to反对，
be pleasant to合某人之意，
be proper to专属，
be polite to礼貌待人，
be rude to粗暴对待，
be relative to与…有关，
be strange to不习惯，
be similar to类似，
be suitable to适合，
be true to忠实，
be thankful to感激，
be useful to对…有用，
be used to习惯。
3.to+名词构成的词组
