句型转换。

1.His father stayed in Shanghai for four months last year. (对划线部分提问)

   ________ ________ did his father ________ in Shanghai last year?

2.The work must be given up. (改为否定句)

   The work ________ ________ given up.

3.Lucy's never been to the Great Wall. (完成反意疑问句)

   Lucy's never been to the Great Wall, ________ ________?

4.Tom came to our school three years ago. (改为同义句)

   Tom ________ ________ ________ our school for three years.

耐火材料按其化学性质可分为哪几种？