涡轮叶片的“喉部”是指:().
A.气流转弯的地方
B.面积最大的地方
C.压力最高的地方
D.面积最小的地方
参考答案:D
用适当的介词填空。
1. Please put _________ your winter jacket. It's cold.
2. I came _________ Friday.
3. Good morning, class! Look _________ the window!
4. They are getting ready _________ school.
5. I like to ski _________ the snow.
制造机器的材料一般使用纯金属。