主动语态与被动语态相互转换，每空一词(含缩写)。
1. We call maths the language of science. (改为被动句)
Maths _________ _________ the language of science.
2. Where did they plant trees? (改为被动句)
Where _________ trees _________?
3. You can borrow two books at a time.(改为被动句)
Two books _________ _________ _________ at a time.
4.The teacher made the students copy the text.改为被动句
The students _________ _________ _________ copy the text.
5. They produce silk in Suzhou.(改为被动句)
Silk _________ _________ in Suzhou.
6. They built a bridge between the two islands last year. (改为被动句)
A bridge ________ ________ between the two islands last year.
7. A birthday party will be given tomorrow. (改为主动句)
We _________ _________ a birthday party tomorrow.
8. John was seen to cross the street just now by someone.(改为主动句)
Someone _________ John _________ the street just now.
9. Can another way be thought of to keep your wine or water warm?(改为主动句)
Can _______ _______ _______ another way to keep your wine or water warm?