句型转换，每空一词。

1. The old worker showed us their new product.（改为同义句）

The old worker _________ their new product _________ _________.

2. Special hairstyles are not allowed in our school. （改为同义句）

Special hairstyles _________ _________ in our school.

3. I know the young man. He is training for the 2008 Olympics.

（合并为含有定语从句的、复合句）

I know the young man _________ _________ training for the 2008 Olympics.

4. John is visiting Tianjin.（改为同义句）

John is _________ _________ _________ _________ Tianjin.

5. The girl is staying at home today. Her mother is ill.

（合并为含有定语从句的复合句）

The girl _________ _________ is ill is staying at home today.

a，b都是不等于0的自然数，且a+1=b，那么a和b的最大公因数是（    ）。