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?
10. Too many trees are still being cut down in the USA. （改为主动句）
_________ are still _________ down too many trees in the USA.
答案：
1. is called 2. were,planted 3. can be borrowed 4. were made to
5. is produced 6. was built 7. will give 8. saw,cross 9. you think of
10. People/They,cutting
