八年级英语 用 if 连接下列句子，注意动词的变化。
现在完成时
1.构成
现在完成时是由助动词 have(has)+动词的过去分词构成。助动词说明该谓语是属于现在时范围。它和主语的人称、数要保持一致。过去分词是主要的谓语动词，说明句子的意义。
2.用法
（1）表示动作发生在过去某个不确定的时间，但对现在留下了某种影响和结果。常被just, already, yet 等副词修饰。常与非延续性动词连用。 如：
-Have you had lunch yet? -Yes, I have. I've just had it. 你（已经）吃午饭了吗？ 我刚刚吃过。（现在我不饿了）
（2）表示从过去某一时刻开始一直持续到现在的动作或状态。这个动作可能刚停止，可能仍然在进行。常用延续性动词，常带有for和since（自从）等表示一段时间的状语。
如：He has taught here since 1981. 他自1981年就在这儿教书。（可能还要继续教）
I haven't seen her for four years. 我有四年没见到她了。
(3）表示说话前发生过一次或多次的动作，现在成为一种经验，一般译为汉语“过”，常带有twice, ever, never, three times等时间状语。
如： I have been to Beijing twice. 我去过北京二次。
3．结构
1）陈述句结构：主语＋have( has)（not）+过去分词＋其它。have not=haven’t has not= hasn’t.
2) 一般疑问句结构：Have( Has )＋主语＋过去分词＋其它？
3) 特殊疑问句：特殊疑问词＋have(has) +主语+ 过去分词＋其它？
e.g. He has already finished his homework.
He hasn’t finished his homework yet.
Has he finished his homework yet? --Yes, he has. / No, he hasn’t. / No, not yet.
4.现在完成时的时间状语
1）现在完成时属于现在时范围，故不能和过去的时间状语连用。如: yesterday, last Sunday, in1990, three years ago等。但是，在强调动作产生的后果和影响时，可以和一些表示不确定的时间状语连用。
a. 用副词already和yet。already一般用于肯定句中，yet一般用于否定句和 疑问句中。如：We have already finished our homework.我们已完成作业了。
They haven't finished their homework yet.他们还没有完成作业。
b. 用ever 和never。多用于否定或疑问句中，表示“曾经”或“从未“等。 如：-Have you ever been to the Great Wall?你曾经去过长城吗？
-I have never been to the Great Wall.我从未去过长城。 c. 用表示到说话为止的过去时间状语，如just（刚刚）, before（以前）, up to now（直到现在）/ until now, in the past (few years/ three days 等), so far (迄今为止) recently 等。 例如：I have seen her before, but I can not remember where. 我以前见过她，但记不起在哪里见过。
He has been there three times the last few days. 近几年他去过那里三次了。 d.用包括“现在”在内的时间状语，如：today, this morning (month ,year, term等.例如：-Have you met him today? - No, I haven't. 今天你见过他吗？我没有。
How many times have you been there this year? 今年你去过那里多少次？
2） 现在完成时可以和带有since或for等表示“一段时间”的状语连用,表示动作或状态从某一时刻开始，一直持续到现在。如：I haven't seen him for two years. 但是，像come, arrive, buy等终止性动词不能与表示“一段时间”的状语连用。要用，必须改为“be（在）”等延续性动词来表述。现归纳总结一下由非延续性动词到延续性动词的转换：
arrive → be here begin (start) → be on die →be dead come back → be back leave → be away fall ill (sick, asleep) → be ill (sick, asleep) go out →be out finish →be over put on →wear 或be on get up →be up join →be in / be a member of… open → be open close →be closed go to school→ be a student borrow →keep buy →have catch(a cold)→ have(a cold) get to know →know begin to study → study come to work→ work
如：He has been a soldier for three years.他参军三年了。或He has been in the army for there years. 不可以说He has joined the army for there years.
His father has been dead for two years.他父亲去世二年了。（不可以说has died）
The film has been on for ten minutes.电影已开始十分钟了。（不可以说has begun）
We have studied English for three years. （不可以说have begun） 我们（开始）学英语已三年了。
5. 现在完成时和一般过去时的区别
现在完成时和一般过去时都表示在过去完成的动作。但现在完成时强调的是这一动作与现在的关系。如对现在产生的结果或影响等，而一般过去时只表示动作在过去某一时刻发生，不表示和现在的关系。试比较：
I have lost my new book. 我把新书丢了。（现在还未找到）
I lost my new book yesterday. 我昨天把新书丢了。（昨天丢的，现在找到与否没说明）
6.几点注意事项 （1）have been(to)与have gone( to)的区别：have been(to) 表示“去过某地（现在已经回来了）”，可用于各人称；have gone(to) 表示“去某地了（说话时某人不在当地）”，常用于第 三人称，前者可与once ,never, several times等连用，后者则不能。如：They have been to Beijing twice.他们去过北京两次。 He has gone to Beijing . 他去北京了。 （2）“It is或has been + 一段时间+ since引导的时间状语从句”表示“某人干某事已经多长时间了”。since从句的谓语要用非延续性动词 若动词延续，则译成相反的意思。如：It is two years since his father died. =His father has been dead for two years.他父亲去世已有三年了。 It is two years since his father lived here. 他爸爸不住这儿已有三年了。 （3）终止性动词现在完成时的否定式，已变成一种可以延续的状态，因此可以和表示一段时间的状语连用。如：I haven't left here since 1997.自从1997年以来，我一直没有离开过这儿。 （4）.提问for短语或since状语用how long。
(5).完成时的否定形式与比较级连用表达最高级含义。如：
I have never seen a better film.我从未看过一部更好的电影。（这部最好）
注：否定式与比较级连用表示最高级含义不一定用于完成时态。如：
--- What about going fishing? --- I can’t agree more.(我再同意不过了哦)
.语法—直接引语变间接引语（多数情况下变为宾语 从句）
(1). 直接引语如果是陈述句，变为间接引语时，用连词that 引导（口语中可以省略引导词）宾语从句。把下列句子变为间接引语或直接引语：
a. “I’ll visit my aunt tomorrow.” Lily said. ____________________________.
b. Our teacher often say to us,” It’s important to finish your homework.”
_______________________________________________________
c. They said they would meet at 9:00 p.m. that night.
“_______________________________________.”they said.
d. Lana said that she wasn’t mad at Marcia anymore.
Lana said’”_______________________________.”
(2). 直接引语如果是一般疑问句，变为间接引语时，变为由连词if 或whether引导的宾语从句。把下列句子变为间接引语或直接引语：
a. “Will you have a surprise party for me?” he asked me.
_______________________________________________
b. She asked Tom,” Can you help me?” ___________________________ c. He asked me if I knew who killed the cat.
He asked ，”__________________________________?”
(3). 直接引语如果是特殊疑问句，变为间接引语时，疑问词不变，宾语从句用陈述语序。把下列句子变为间接引语或直接引语：
a. The teacher asked,” Why are all the windows open?”
______________________________________________.
b. “When will you find out the time?” she asked me.
______________________________________________.
c. “What’s the matter with you, Alice?” he asked.
_____________________________________
d. They asked me where my friends were.
____________________________________________
(4).直接引语如果是肯定型祈使句，变为间接引语时，谓语变为tell sb. to do 或ask sb. to do 等句式。把下列句子变为间接引语或直接引语：
a. “Make sure the door is closed，” she said to her little son.
____________________________________________________.
b. “Tell me the news, please.” Li Hui said to me.
____________________________________________________.
c. He asked me to take care of his pet dog.
“_______________________________，” he said to me.
(5).直接引语如果是否定型祈使句，变为间接引语时，谓语变为tell sb.not to do 或ask sb. not to do等。把下列句子变为间接引语或直接引语：a. “Don’t smoke in the room,” he said to me.
________________________________________________.
b. “Don’t shout at the old man,” I said to him.________________________
c. Our teacher told us not to talk in class.
“____________________________, “ our teacher said to us.
d. My mother told me ___ others when they are in trouble.
A. not to laugh at B. don’t laugh at C. not laugh at D. never laugh at
2. if 条件句 在一般将来时的句子里（指主句），时间状语从句、条件状语从句等的谓语动词用一般现在时代替将来时。当主句含有情态动词或主句为祈使句时，从句也用一般现在时。如：You must pay for it if you lose it.
附加疑问句
附加疑问句由“陈述句 + 附加疑问句”两部分构成。一般有两种形式：前肯后否或前否后肯。对附加疑问部分应注意以下几点： 1）主语只能用人称代词；2）附加疑问句的not必须与（be /助/情）缩写；3）附加疑问句的时态必须与陈述部分的时态一致。
Tom is a worker, isn’t Tom? (改错) _______ You can swim, can not you? ( 改错) ______
特别注意以下几种反意疑问句
1.陈述部分含否定意味的词如few,little,never,nothing,nobody,no,hardly,none,seldom等时，附加疑问句应使用肯定形式；但如果陈述句部分含有un-, in-, im-, dis-等否定前缀构成的派生词时，该陈述句部分仍做肯定处理，疑问部分用否定形式。
He hardly speaks English, does he? They are unhappy, aren’t they?
2. this/that作主语时，无论是否指人，疑问部分用it；these/those用they。
This is your brother, isn’t it? Those are books,_______________?
3.陈述部分的主语如果是one, 疑问部分主语用one或he。One can’t be always young, can one/ he?
4.陈述部分的主语是everything, something, nothing, anything时，附加疑问句的主语应用it；陈述部分的主语是everybody, somebody, nobody, everyone, no one时，附加疑问句的主语应用they或he。
Everything is ready, ___________? Everyone is here, ____________?
5.陈述部分是祈使句时，附加疑问句一般用：will you? 但注意：
Let’s…（包括听者在内）, 附加疑问句一般用shall we? Let us/him/me …（不包括听者在内）， 附加疑问句一般用will you? Let’s go for a walk, shall we? Let him come in, will you?
6.陈述部分是there be结构时，应用be there?结构来完成。 There’s little water, _________？
7..陈述部分含that引导的宾语从句时，疑问部分通常与主句一致。但当主句陈述部分是”I / We think (believe, suppose) +宾语从句”时，附加问句应与从句一致。I’m sure + 宾语从句也是如此
1).She said I did it, _________? 2)We don’t think you are right，________?
3) I’m sure you’ll help me, ____________?
8.如果陈述部分是I am… , 附加疑问部分为aren’t I? I am older than you, __________?
9.陈述部分含had better, would like时， 疑问部分分别用hadn’t…?和wouldn’t…? You’d better go out , _______________? You’d like to go there, ____________________?
10.陈述部分是感叹句，附加问句的人称代词应与主语一致，疑问部分用否定形式。 What a kind girl, isn’t she? What a fine day, ___________?
11.the+形容词表示一类人，其附加疑问句主语用复数代词。 The poor had no right to speak at that time, did they?
12. 由neither…nor，either… or ， not only…but also ， both…and ， not…but，…or…， …and…等连接的并列主语，附加疑问部分用复数。
Neither you nor I am wrong, are we? Both Jack and Tom went there, didn’t they?
13.当陈述部分含有have to时，附加疑问部分的助动词应根据have 的变化，分别用don’t， doesn’t， didn’t。 He has to take your advice, doesn’t he?
14.当陈述部分的主语是从句、不定式、动名词或词组时，附加疑问部分的主语通常用it。 What he said at the meeting is very important, isn’t it? Swimming in rivers is a good sport, _____________?
15.当陈述部分含有wish时，附加疑问部分的助动词用may。I wish to use your computer, may I?
16. 当陈述部分的谓语是“used to+动词原形（过去常常干某事）”时，疑问部分用“didn’t+主语”或“usedn’t +主语”。 He used to live in London, didn’t he? / usedn’t he?
if we protect tigers ,more of them will be there.
您好，很高兴为您解答问题。1、I will go to the park.It will not rain tomorrow.
I will go to the park，if it doesn't rain tomorrow.
2. He won’t help others. He will never get others’ help.
If he doesn't help others， he will never get others’ help.
3. I will pass the exams. I’ll go to high school.
If I pass the exams， I’ll go to high school.
4. She will become a doctor. She’ll make a lot of money.
If She becomes a doctor，She’ll make a lot of money.
5. My father will save more money. He will stop smoking.
My father will save more money，if he stops smoking.
望采纳，谢谢。（绝对正确）
1.If it doesn't rain tommorrow，I will go to the park.
2.If he doesn't help others，he will never get other's help.
3.If I pass the exam，I will go to the high school.
4.If she becomes a doctor，she will make a lot of money.
5.If my father stops smoking，he will save more money.
1.i will go to the park if it doesn't rain tomorrow
2.he will never get others' help if he never help others.
3.i'll go to high school if i pass the exams.
4.she'll make a lot of money if she becomes a doctor.
5.my father will save some money if he stops smoking.
手写记得大小写哦
lf it doesn`t rain ,l will go to the park tomorrow.
lf he don`t help others,he will never get other`s help.
lf l pass the exam, l will go to high school.
lf she become a doctor,she will make a lot of money.
lf my father stop smoking,he will save more money.
原昌京必： If it does't rain ,I will back home. If I feel board,I will watch the TV. If I feel tried,I will go bed early. If I get up early,I will be very happy. 如果我开心,妈妈就会@%$@#$!! 应该很容易吧
隆回县13793663912： 用if改写或连接下列句子 - ？
原昌京必： 题意大概是将原来陈述句,用if反写出来. 例如第1句,句意是:他不是学生,他不可以参加演讲.如果用if改写的话,意思就要变成,如果他是学生的话,就可以参加演讲了. 1.If he was a student,he could attend the lecture. 2.If I am you ,I can make the decision. 之后的以此类推.
隆回县13793663912： 初二英语下册的IF的用法？
原昌京必： if 如果表示“是否”的意思时,后面跟什么时态都可以,如:I don't know if he will come tomorrow. 我不知道他明天是否来.但如果它的意思是“如果”,就只能用一般现在时代替将来时.如:If it rains tomorrow, we won't go there. 如果明天下雨,我们将不去那里
隆回县13793663912： 初二英语if宾语从句？
原昌京必： 宾语从句在句子中起宾语作用的从句叫做宾语从句.宾语从句分为三类:动词的宾语从句,介词的宾语从句和形容词的宾语从句.1.宾语从句的连接词从属连词连接宾语从句的从属连词主要有that,if,whether.that引导表示陈述句的宾语从句,而if和...
隆回县13793663912： 八年级英语中,if和 whether怎么用? - ？
原昌京必： 一般时候两者可以替换,但是下列几种情况只能用Whether:1:当从句中紧跟or not时,例如:We didn't know whether or not she was at home.2:当构成不定式to do结构时,例如:She doesn't decide whether to tell her husband the truth.3:在介词之后,例如:It all depends on whether the weather is fine.4:discuss后面只能用whether,例如:They discussed whether they could go there by bike.希望可以帮助你,加油!
隆回县13793663912： 英语:按要求改写下列句子 - ？
原昌京必： 1、(An accident )will happen if you drive carelessly.对括号内部分进行提问 ( what )( will )happen if you drive carelessly? 2、If you keep practicing,you will improve your English.改写同义句 ( keep )practicing,( and )you will improve your ...
隆回县13793663912： 用if连接下列句子、？
原昌京必： 1.If it's fine tomorrow,we'll go to the Great Wall. 2.If we win a lot of money,I'll come here on Sunday. 3.If I am free,we'll travel around the world. 4.If you don't hurry,we'll miss the train. 5.If it rains tomorrow,we'll miss the train.
隆回县13793663912： 初二英语,急~~~~？
原昌京必： 1. won't take any....or 2. don't......should 3. What will....do 4. How will....go 5. she liked 6. told me...not to 7. 这个句子给错了,我给整个句子的答案:If you don't hurry up, you will be late. 8. doesn't rain....will go
隆回县13793663912： 这三个英语句子各是因为什么用whether或if连接的?后两个句子可以把whether换成if吗? - ？
原昌京必： 因为这个是一般疑问句(did you /do you等而不是when/where/how/what/which 等特殊疑问句),所以转换为间接引语的时候,就要用if或者whether进行引导,如果是特殊疑问句,保留when/where/how/what/which 即可.后两个句子可以把whether换成if,只有当有whether,,,or not,才只能用whether
