1 . Someone is knocking at my door.   It must be Tom. (合并为一句)
It _______ be Tom_______ at my door.

2 . 句型转换,按要求完成下列各题
1. Every year it receives over 750，000 visitors. (改为同义句)
It receives _______ _______ 750，000 visitors every year.
2. The beautiful sweater on the bed is his sister’s. (改为同义句)
The beautiful sweater on the bed_______ _______ his sister.
3. Charlie is so young that he can’t take the underground alone. (改为简单句)
Charlie is_______ _______to take the underground alone.
4. Mrs. Black often stops her son playing computer games. (改为同义句)
Mrs.   Black often_______ her son _______ _______computer games.
5. Someone is knocking at my door.   It must be Tom. (合并为一句)
It _______ be Tom_______ at my door.