下列不属于棘轮机构工作特点的是（）
A．冲击振动较大
B．常用于牛头刨床工作台的横向进给机构
C．传递动力较大
D．常用于起重设备的止回机构
参考答案：C
按要求改写句子。
1. How's the weather in Singapore? (改为同义句)
the weather in Singapore?
2. —____ ? (看答语写问句)
—It's great.
3. There is a lot of rain in the south of China this year. (改为同义句)
often____ in the south of China this year.
4. Tom wears a shirt because it's hot here. (对划线部分提问)
Tom wear a shirt?
5. He plays computer games every morning. (改为现在进行时)
He _____ computer games now.
人体中最坚硬的钙化组织是（）。
A.牙釉质
B.牙本质
C.牙骨质
D.蛋白质
E.以上都不是
