构成的时间状语连用。

No books have been bought since last week.

自上周以来，没有人来买书。

(3)短语动词是一个不可分割的整体，在被动语态中要保持完整性，其中的介词或副词不可省略。

It is said that the problem has been looked into.

据说已经调查了这个问题。

(4)只带有一个宾语的动词变为被动语态时，将主动语态的宾语变为被动语态的主语。

We have built many houses in the past ten years.

→Many houses have been built in the past ten years.

(5)带有双宾语的动词，如give，send，bring，take，teach，show，tell，make，sing，write，read，sell，buy，pay，lend，pass，promise等，变为被动语态时，可将其中一个宾语变为主语，另一个保留不动。

We have given him the book.

→He has been given the book.

→The book has been given to him.

(6)带有复合宾语的动词变为被动语态时，只能将宾语变为主语，原来的宾补改为主语补足语。原来用省略to的不定式作宾补的，被动语态中要用带to的不定式。

I have told them to help you.

→They have been told to help you.

Ⅰ.单句语法填空

1．Sarah has been told/was told(tell) that she could be Britain's new supermodel，earning a million dollars in the next year.(2017·全国Ⅲ)

2．In recent years，stress has been regarded(regard) as a cause of a whole range of medical problems.(2016·上海)

3．Despite the previous rounds of talks，no agreement has been reached(reach) so far by the two sides.(2015·天津)