A. Useful expressions

1. for a while 一會兒， 它可用于一般時，過去時，將來時，完成時，常與持續(xù)性動詞連用。

We talked with each other for a while.

I haven’t heard from him for quite a while.( for quite a while=for a long time)

Cf: after a while 過一會， 一會兒后， 常與終止性動詞的一般過去時連用。

After a while they started out.

2. cut off ----- shut off（電路）切斷，停（水，電）

The electricity was cut off for several days.

3. stay up -----not fall down ,not go to bed

I stayed up until Father came back.

4. for ever (AE forever)終身

We’ll remember him for ever.

5. a (large/great)number of., a great many許多與復數(shù)名詞或代詞連用

I have a number of letters to write.

There are a large number of places to visit in Beijing.

A great many words and expressions have come into the language from American English.

Cf: the number of 是……的數(shù)量，謂語動詞常用單數(shù)

The number of pages in this book is 500 hundred.

6. time 作“倍數(shù)”解，是可數(shù)名詞，如 three times four times ，但兩倍要用 twice

1)表示甲比已乙大（高，長，寬等）幾倍的句型是：

A is three( four etc.) times larger/bigger(higher, longer, wider,etc.) than B.

Their school is three times larger than ours.

2) 表示甲是乙的幾倍大（高，長，寬等）的句型是：

A is three (four,etc. )times as big (high ,long,wide,etc.)as B.

Asia is four times as large as Europe.

當然這兩個句型可以互換但要注意準確性。

This street is three times longer than that one.

This street is four times as long as that one.

7. afraid 的幾種用法。

1)be afraid of sth. 害怕……

The little girl is afraid of dogs.

2)be afraid to do sth. 害怕/不敢做某事

Tom lost the money and was afraid to tell his mother.

3)be afraid that （從句） 恐怕……

I’m afraid that I’ll be late.

B. Grammar. 定語從句，請看書P。158----159。