1.一般现在时的被动语态构成：is / am / are + 及物动词的过去分词
Our classroom is cleaned everyday.
I am asked to study hard.
Knives are used for cutting things.
- 一般过去时的被动语态构成：was / were + 及物动词的过去分词
A new shop was built last year.
Dinosaur eggs were laid long long ago.
- 现在完成时的被动语态构成：has / have + been + 及物动词的过去分词
This book has been translated into many languages.
Many man-made satellites have been sent up into space by many countries.
- 一般将来时的被动语态构成：will+ be + 及物动词的过去分词
A new hospital will be built in our city.
Many more trees will be planted next year.
- 含有情态动词的被动语态构成：情态动词+ be + 及物动词的过去分词
Young trees must be watered often.
Your mistakes should be corrected right now.
The door may be locked inside.
Your homework can be handed in tomorrow.
- 现在进行时的被动语态构成：am / is / are + being + 及物动词的过去分词
Uncle Wang is mending my bike now.→ My bike is being repaired by Tom now. They are planting trees over there. → Trees are being planted over there by them.
- 不定式的被动语态：to + be + 及物动词的过去分词
There are two books to be read. → There are twenty more trees to be planted.二、 怎样把主动语态改成被动语态?
例：1. Bruce writes a letter every week. →A letter is written by Bruce every week. 2. Li Lei mended the broken bike this morning.→The broken bike was mended by Li Lei this morning.
- He has written two novels so far.→Two novels have been written by him so far. 4. They will plant ten trees tomorrow.→Ten trees will be planted by them tomorrow. 5. Lucy is writing a letter now.→A letter is being written by Lucy now.
- You must lock the door when you leave.→the door must be locked when you leave. 三、 使用被动语态应注意的几个问题：
What will happen in 100 years.
The dinosaurs disappeared about 65 million years ago.