汽机减负荷停机过程中，蒸汽流量逐渐减小，当蒸汽温度不变时，汽缸的热应力变化是（）。
A、增加；
B、减少；
C、不变。
参考答案：A
根据句意及汉语提示写单词。
1. Tom made an interesting _______ (演讲) last time.
2. Everyone should keep away from _______(毒品) as far as possible.
3.—How many students were _______(缺席的) from today’s English class?
—Only one.
4. Most of my classmates like learning _______(生物学).
5.—How many people were _______ (出席的) at the meeting?
—Two hundred.
高速钢车刀加工灰铸铁时前角一般为（）。
A.0°～5°
B.6°～8°
C.10°～15°
D.30
(演讲) last time.