Ⅲ. 句型转换。
1. It's very hard to work out the math problem. (改为同义句)
______ ______ ______ the math problem is very hard.
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. (改为否定句)
Maria ______ ______ to finish her homework first.
5. We can explore the graves of ancient Chinese emperors. (对画线部分提问)
______ ______ we explore?

【解析】：1. 原句意为“解这道数学题很难”，“It's + adj. + to do sth.”可转换为“To do sth. is + adj.”，所以此处填“To work out”。
2. 原句是“I would like...”结构，改为一般疑问句时将“would”提前，第一人称“I”变为第二人称“you”，“my”相应变为“your”，所以填“Would you；your”。
3. “How about...”表示提建议，肯定回答常用“Good idea!”或“That's a good idea!”，此处简洁回答用“Good idea”。
4. 原句“has to”表示“不得不”，否定形式需借助助动词“doesn't”，后面接动词原形“have”，所以填“doesn't have”。
5. 画线部分“the graves of ancient Chinese emperors”是宾语，对其提问用疑问词“What”，原句有情态动词“can”，将其提前，所以填“What can”。
【答案】：1. To work out
2. Would you；your
3. Good idea
4. doesn't have
5. What can