英文文法
被動語態(1)
謂語動詞的語態表示句子的主語和謂語動作之間的關係-1）當句子的主語是謂語動作的執行者時，主、謂之間的關係稱為主動語態；2）當句子的主語是謂語動作的承受者時，主、謂之間的關係稱為被動語態。例如：
I teach English.（主動語態）我教英語。
Our English is taught by him.（被動語態）我們的英語是由他教的。
He speaks English.（主動語態）他說英文。
English is spoken in many countries all over the world.（被動語態）世界許多國家都講英語。
在被動語態的句子中，謂語部分的結構是be + p.p.（過去分詞）。被動語態的句子有時態的變化，這個變化反映在be動詞上。也就是說，把一個句子做成被動語態的句子，只需要寫出BE動詞的所需時態，再加上所給動詞的過去分詞就行了。當然，這只是指謂語部分而言。我們知道，be動詞作為一個獨立的謂語動詞有自己現在分詞（being）和過去分詞 （been）。那麼，下面我們來看看be在各種時態中的變化形式：
一般現在時 am / is / are
一般過去時 was / were
一般將來時 shall / will + be
過去將來時 would / should + be
現在進行時 am / is / are + being
過去進行時 was / were + being
現在完成時 have / has + been
過去完成時 had + been
說明：1）以上的八個時態可用於被動式，其他沒有列舉的時態都不宜用於被動語態的句子中。2）另外，表中被斜線隔開的詞表示，供根據具體情況作選擇。弄清楚了be在各種時態中的變化形式以後，我們就能很輕鬆地寫出被動語態的各種時態了。我們可看看下面的實例：
English is spoken in many countries all over the world .（一般現在時）
世界上許多國家都講英文。
Some TV sets for sale in the department store were stolen last night. （一般過去時）
那家商場用來出售的部分電視機昨晚被盜。
He won't be allowed, by his father, to marry Larra. （一般將來時）
他父親不會讓他娶拉拉為妻的。
They would be sent to the army when they finished the training. （過去將來時）
他們結束訓練時將被派往部隊。
The project is being carried out.（現在進行時）
這個計畫正在執行中。
The case was being investigated then.（過去進行時）
那時這案子正在調查中。
This novel has been translated into several languages.
（現在完成時）這本小說已被譯成了幾種語言。
They said that production costs had been reduced.
（過去完成時）他們說生產成本已經下降了。
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被動語態 (2)
一般來說，在我們日常生活中，能用主動語態的時候就儘量不去用被動語態。
只有在下列情況中我們才用被動語態：
1）不清楚動作的執行者是誰, 例如:
The front window in the classroom was broken yesterday. 昨天，教室的前窗被打破了。
The time-table has been changed .時間表已變動了。
We haven't been informed of it .還沒有人通知我們這事兒。
2)說話人對賓語的興趣大於對主語的興趣（這時可用by引導出動作的執行者），例如：
My TV set is being repaired in the shop. 我的電視機正在這店裏修。
These books are written especially for children. 這些書是專門為孩子們寫的。
The song was composed by a young worker. 這首歌是一位年青工人譜寫的。
3) 不願意說出動作的執行者，其目的是為了使語言得體、圓滑等。在這種情況下，有時常用一些句式，如"It is said that…"（據說……），"It is reported that …"（據報導……），"It is rumoured that …"（據傳言……）等等。例如：
You are requested to make a speech at next meeting. 請您在下次會議上作個發言。
It is said that she is going to be married to a foreigner. 據說她要嫁給一個外國人。
It is rumored that he has been appointed as successor to the president of our company . 據傳聞，他已被任命為我們公司總裁的接班人了。
It is generally considered impolite to ask one's age, salary, marriage, etc.. 問別人的年齡、工資、婚姻狀況等通常被認為是不禮貌的。
4) 出於修辭的原因，或是說為了更好地安排句子。例如：
The professor came to our school and warmly welcomed by the teachers and students.（句子的後半句用被動式就可以只安排一個主語。）那位教授來到我校並受到師生們的熱烈歡迎。
I went to the party and was asked by my friends to do some cooking for them. （同上）我去參加了那個聚會，朋友們還請我為他們燒了幾樣菜。
The notion is especially opposed to by those who have invested much in the area.
（此句若選those作主語，就會使主語與謂語相距太遠而顯得句子鬆散，因為它的定太長了。）這個提議特別遭到了那些在本地區投資很大的人的反對。
這裏我們還要進一步談談幾種特殊的被動結構。
1）關於帶情態動詞的被動結構
帶情態動詞的被動結構的固定句式為"情態動詞 + be + 過去分詞"。也有個別帶"to"的情態動詞例外，如：ought to和have to ，它們的被動結構就只能在不定式中。例如：
The debt must be paid off before next month. 那筆債務必須在下個月前付清。
The debt has to be paid off before next month. 那筆債務必須在下個月前付清。
Oil can be turned into energy by burning it. 油經過燃燒可變為能原。
You ought to be criticized for your carelessness. 你由於粗心大意應當受到批評。
2) 關於帶有兩個賓語的主動態變成被動態
我們先來看看"帶有兩個賓語的主動態句子的結構"，重點看謂語部分 ：
She sent me a novel on my birthday .
主 謂 間接賓語 直接賓語 狀語
I allowed him an hour to finish the work .
主 謂 間接賓語 直接賓語 狀語
從上面的分析可以看出，兩個賓語分別是：直接賓語和間接賓語。將這種主動態的句子變成被動態的句子，可選兩個賓語中的任何一個作為被動態句子的主語，而將另一個賓語作為"保留賓語"寫入被動態的句中。但有一點要說明，那就是，如果你選直接賓語作"主語"，有時要在被動態句子的"保留賓語"前加上合適的介詞。因為這些動詞常有兩種句式，即：我們可以說give sb sth , send sb sth , buy sb sth ；我們也可以說give sth to sb, send sth to sb , buy sth for sb 。請看下面兩種情況的對照：
She sent me a novel on my birthday. (主動)
I was sent a novel on my birthday. (被動)
A novel was sent to me on my birthday. (被動)
My brother bought me a watch yesterday. (主動)
I was bought a watch yesterday. (被動)
A watch was bought for me by my brother yesterday.(被動)
3)關於帶有複合賓語的主動態變成被動態
如果將帶有複合賓語（既：賓語 + 賓語補足語）的主動態的句子變成被動態的句子，我們只能選擇原來句子的賓語作被動態句子的主語；而這時，原句裏的賓語補足語現在就變成被動態句子的"主語補足語"了。例如：
The story made us laugh .(賓語補足語)
We were made to laugh by the story. (主語補足語)
They asked me to help them. (賓語補足語)
I was asked to help them. (主語補足語)
We saw them coming over. (賓語補足語)
They were seen coming over. (主語補足語)
連詞
一、連詞屬於虛詞之一，它不能在句子裏獨立地擔任句子成分，而只能起連接作用--連接詞與詞、短語與短語、句子與句子。例如：
Would you like some tea or coffee? （連接詞與詞）您是喝茶，還是喝咖啡？
Do we have our meeting in the morning or in the afternoon?
（連接短語與短語） 我們是上午開會，還是下午開會？
Do it carefully, or you'll make some mistake.
（連接句子與句子）認真地幹，不然會出差錯的。
二、連詞主要可分成兩類：
並列連詞（Coordinating Conjunctions）
並列連詞用來連接平行對等（即互不從屬）的詞、片語、或分句。按其表示的不同意思有下面幾種：
1）表示轉折意思 but , yet , however , nevertheless
2）表示因果關係 for , so , therefore , hence
3）表示並列關係 and , or , either…or , neither…nor , not only…but (also) , both…and , as well as
從屬連詞（Subordinating Conjunctions）
從屬連詞是用來引起從句的，它在主句和從句中間起連接作用。具體地說，從屬連詞主要引起名詞從句（主語從句、賓語從句、表語從句、同位語從句）和狀語從句，不會引起定語從句。
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引起名詞從句的連詞：
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that , whether , if
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引起狀語從句的連詞
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時間狀語從句：
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when , whenever , as , while, before , after, until, till, since, ever since, once, as soon as, every time, the moment, instantly, directly
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地點狀語從句：
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where , wherever
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原因狀語從句：
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as, because, since, seeing(that) , considering (that) , now that , not that…but that
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目的狀語從句：
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that , so that , in order that , lest , for fear that , in case
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結果狀語從句：
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that , so … that , such … that
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條件狀語從句：
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if , unless , suppose , supposing ,so/as long as, so far as, on condition(that ) ,provided ( that )
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讓步狀語從句：
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though , although , no matter , even if , even though , however , whatever
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比較狀語從句：
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than , as
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方式狀語從句：
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as , as if , as though
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比較while, when, as
1）as, when 引導短暫性動作的動詞。
Just as / Just when / When I stopped my car, a man came up to me.
2）當從句的動作發生於主句動作之前，只能用when 引導這個從句，不可用as 或 while。
When you have finished your work, you may have a rest.
3）從句表示"隨時間推移"連詞能用as，不用when 或while。
As the day went on, the weather got worse.
日子一天天過去，天氣越變越壞。
並列連詞與並列結構
並列連詞引導兩個並列的句子。
1)and 與or
判斷改錯：
(錯) They sat down and talk about something.
(錯) They started to dance and sang.
(錯) I saw two men sitting behind and whisper there.
(對) They sat down and talked about something.
(對) They started to dance and sing.
(對)I saw two men sitting behind and whispering there.
解析：
第一句： and 連接兩個並列的謂語，所以 talk 應改為 talked。
第二句：and 連接兩個並列的動詞不定式，第二個不定式往往省略to，因此sang 應改為 sing。
第三句：and 連接感觀動詞saw 後面的用作的賓補的兩個並列分詞結構，因此whisper應改為whispering。
注意：and 還可以和祈使句或名詞片語連用表示條件。（or也有此用法）
Make up your mind, and you'll get the chance.
= If you make up your mind, you'll get the chance.
One more effort, and you'll succeed.
= If you make one more effort, you'll succeed.
2) both …and 兩者都
She plays (both) the piano and the guitar.
3) not only…but (also), as well as不但…而且）
She plays not only the piano, but (also) the guitar.
注意： not only… but also 關聯兩個分句時，一個分句因有否定詞not 而必須倒裝。
Not only does he like reading stories, but also he can even write some.
4) neithe…nor 意思為"既不……也不……"謂語動詞採用就近原則，與nor後的詞保持一致。
Neither you nor he is to blame.
情態動詞+ have +過去分詞
1) may(might) have + done sth, can (could) have + done sth 表示過去，推測過去時間裏可能發生的事情。
Philip may (might) have been hurt seriously in the car accident.
Philip can (could) have been hurt seriously in the car accident.
2) must have +done sth，對過去時間裏可能發生的事情的推測，語氣較強，具有"肯定"，"諒必"的意思。
---Linda has gone to work, but her bicycle is still here.
---She must have gone by bus.
3) ought to have done sth, should have done sth
本應該做某事，而事實上並沒有做。否定句表示"不該做某事而做了"。
You ought to (should) have been more careful in this experiment.
He ought not to have thrown the old clothes away.（事實上已扔了。）
ought to 在語氣上比should 要強。
4) needn't have done sth 本沒必要做某事
I dressed very warmly for the trip, but I needn't have done so. The weather was hot.
5) would like to have done sth 本打算做某事
I would like to have read the article, but I was very busy then.
比較can 和be able to
1）can could 表示能力；可能 (過去時用could),
只用於現在式和過去式(could)。be able to可以用於各種時態。
They will be able to tell you the news soon. 他很快就能告訴你消息了。
2）只用be able to
a. 位於助動詞後。
b. 情態動詞後。
c. 表示過去某時刻動作時。
d. 用於句首表示條件。
e. 表示成功地做了某事時，只能用was/were able to， 不能用could。
He was able to flee Europe before the war broke out.
= He managed to flee Europe before the war broke out.
注意：could不表示時態
1）提出委婉的請求，（注意在回答中不可用could）。
--- Could I have the television on?
--- Yes, you can. / No, you can't.
2）在否定，疑問句中表示推測或懷疑。
He couldn't be a bad man.
他不大可能是壞人。
比較have to和must
1) 兩詞都是'必須'的意思，have to 表示客觀的需要， must 表示說話人主觀上的看法，既主觀上的必要。
My brother was very ill, so I had to call the doctor in the middle of the night.
我弟弟病得很厲害，我只得半夜裏把醫生請來。(客觀上需要做這件事)
He said that they must work hard. 他說他們必須努力工作。（主觀上要做這件事）
2) have to有人稱、數、時態的變化，而must只有一種形式。但must 可用於間接引語中表示過去的必要或義務。
He had to look after his sister yesterday.
3） 在否定結構中：
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