题目内容：

1.They heard a message from a spacecraft.(用just改为现在完成时态形式)

They        just        a message from a spacecraft.

2.Have you got a letter from Lucy?(改为同义句)

Have you                Lucy?

3.To understand the problem is very difficult.(用it作为形式主语)

               very difficult        understand the problem.

4.I came here two days ago.(改为同义句)

I                here         two days.

5.Her mother has been to Hong Kong several times.(就画线部分提问)

                        has her mother been to Hong Kong?