1构成：
主动语态 被动语态
现在完成时 have/has done----------àhave/has been done
He has been sent to study the new technology in the company.
The dirty clothes have not been washed.
Have the windows been cleaned?
How many shopping centers have been built in this city?
2. 只有及物动词才有被动语态，不及物动词（词组）没有被动语态, 如:happen, take place,
die, appear, disappear, fail, remain, lie, last, sit ,stand, break out, come true, belong to等．如：
What has happened to your brother?
3．但许多不及物动词加介词或副词构成的短语动词，相当于及物动词，也可以有被动语态。
但短语动词是一个不可分割的整体，变为被动语态时，不可丢掉构成短语的介词或副词。如：
The child has been taken good care of by Grandma Wang all these years.
A notice has been put up on the wall
