句型转换。

1. It's very hard to work out the math problem. (同义句)  

     ______ the math problem is very har.

2. I would like to come to China for my vacation. (改为一般疑问句)  

     ______ like to come to China for ______ vacation.

3. How about taking him to the Ming Tombs? (作肯定回答)  

    ______ ______!

4. Maria has to finish her homework first. (否定句)  

    Maria ______ ______ to finish her homework first.

5. We can explore the graves of ancient Chinese emperors. (就划线部分提问)  

     ______ ______ we explore?