1. 同位語從句跟在名詞后面,進一步說明該名詞的具體內(nèi)容。引導(dǎo)同位語從句的名詞主要有 fact, news, promise, idea, truth等。連接詞用that (不用which)及連接副詞how, when, where, why等。
2. 關(guān)聯(lián)詞只能用whether不能用if表示“是否”的情況如下:
1)在表語從句和同位語從句中。
The question is whether the film is worth seeing.
The news whether our team has won the match is unknown.
2)在主語從句中,只有用it作形式主語時,whether和if都能引導(dǎo)主語從句,否則,也只能用whether。
Whether we shall attend the meeting hasn't been decided yet.
It hasn't been decided whether (if) we shall attend the meeting.
3)在介詞之后(介詞往往可以省略)
It all depends (on) whether they will support us.
4)后面直接跟動詞不定式時。 He doesn't know whether to stay or not.
5)后面緊接or not 時。 We didn't know whether or not she was ready.
6)引導(dǎo)讓步狀語從句,只能用whether。 Whether you like it or not, you must do it well.
7)用if會引起歧義時。
Please let me know if you like it. 該句有兩個意思:“請告訴我你是否喜歡”.或“如果你喜歡,請告訴我?!庇脀hether就可以避免。
3. 在下面幾種情況下必須用“that”引導(dǎo)定語從句:
1)先行詞是不定代詞:all, few, little, much, something, nothing, anything等。 All that we have to do is to practice every day.
2)先行詞被序數(shù)詞或形容詞最高級所修飾。 The first lesson that I learned will never be forgotten.
3)先行詞被all, any, every, each, few, little, no, some, 等修飾。 I have read all the book (that) you gave me.
4)先行詞被 the only, the very, the same, the last 修飾時。 He is the only person that I want to talk to.
5)先行詞既有人又有物時。 They talked of things and persons that they remembered in the school.
4. 先行詞是表示地點時,要根據(jù)從句的謂語動詞是及物的還是不及物的。如果是及物的就用that(which),否則用where。
This is the house where he lived last year. This is the house that (which) he visited last year.
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