按要求改写下列各句，每空一词。
1. I need a computer. (改为否定句)
I ________ ________ a computer.
2. The books are under the bed.(对画线部分提问)
________ ________ the books?
3. He can play football.(改为一般疑问句)
________ ________ play football?
4. There are four girls over there. (改为否定句)
There________ four girls over there.
5. Is that your bookcase? (作肯定回答)
________, ________ ________.
