英语知识

（错）I have received his letter for a month.

（对）I haven’t received his letter for almost a month.

12. 比较since和for

Since 用来说明动作起始时间，for用来说明动作延续时间长度。

I have lived here for more than twenty years.

I have lived here since I was bornM 1976.

I have known Xiao Li since she was a little girl.

My brother has been in the Youth League for two years.

I have not heard from my uncle for a long time.

注意：并非有for 作为时间状语的句子都用现在完成时。

I worked here for more than twenty years.

(我现在已不在这里工作。)

I have worked here for many years.

(现在我仍在这里工作。)

小窍门： 当现在完成时+一段时间，这一结构中，我们用下面的公式转化，很容易就能排除非延续动词在完成时中的误使。

1) (对) Tom has studied Russian for three years.

= Tom began to study Russian three years ago, and is still studying it now.

2) (错) Harry has got married for six years.

= Harry began to get married six years ago, and is still getting married now.

显然，第二句不对，它应改为 Harry got married six years ago. 或 Harry has been married for six years.

13. since的四种用法

2) since +一段时间+ ago

I have been here since five months ago.

3) since +从句

Great changes have taken place since you left.

Considerable time1）主语句中有一个宾语的被动语态，如：

He saw her in the shop yesterday.

She was seen in the shop yesterday.

2) 主语有两个宾语的被动语态

Li Lei gave me a chemistry book.

I was given a chemistry book by Li Lei.

A chemistry book was given to me by Li Lei.

3）主动句中含宾语补足语的句子的被动语态

若宾语补足语是不带to 的不定式，变为被动语态时，该不定式前要加"to"。此类动词为

可--> He was seen to play football on the playground.

若宾语补足语是带to的不定式，那么被动语态仍保留to:

Mother told me not to be late

I was told not to be late环境，构成被动语态。

Coal can be used to produce electricity for agriculture and industry.

6）表示"据说"或"相信" 的词组

believe, consider, declare, expect, feel ,n report, say, see, suppose, think, understand

It is said that… 据说

It is reported that… 据报道

It is believed that… 大家相信

It is hoped that… 大家希望

It is well known that… 众所周知

It is thought that… 大家认为

It is suggested that… 据建议

It is taken granted that… 被视为当然

It has been decided that… 大家决定

It must be remember 务必记住的是

It is said that she will leave for Wuhan on Tuesday.