句型转换。
1. They're having a music class. (就划线部分提问)
_______ class _______ they having?
2. It's Friday today. (同上)
_______ _______ is it today?
3. We play the piano twice a week. (同上)
_______ _______ do you play the piano?
4. He usually goes to Beijing by sea. (同上)
_______ _______ he usually go to Beijing?
5. I don't like this motorcycle because it's too old. (同上)
_______ _______ you like this motorcycle?
，则f′(x)=（）。