紧急放风阀受()的空气压力在短时间内的压差来控制其动作。
A.列车管
B.总风管
C.作用风缸
D.紧急风缸
参考答案:A, D
With the increase of the people’s income, there is a growing ______ for Chinese students to go abroad for further education.
A.tendency
B.consciousness
C.accountant
D.conception
作业许可证的有效期限一般不超过一个()。
A.班次;
B.天;
C.周;
D.月。