按要求改写句子。
1. Can you help him? (肯定句)
__________________________________________________
2. He is writing a letter. (就划线部分提问)
__________________________________________________
3. They are reading the newspaper. (改为否定句)
__________________________________________________
4. Bob is playing football. (改为一般疑问句)
__________________________________________________
5. He is cooking meat. (改为一般疑问句)
__________________________________________________
6. Is your mother watching TV? (否定回答)
__________________________________________________
