动液面波动范围超过±（）m必须查明原因或复测验证。
A、50
B、100
C、150
D、200
参考答案：D
选择填空。
You ______ your clothes now. [ ]
A. had better to wash
B. had better wash
C. had better washing
D. would better wash
甲乙二人都以不变的速度在环形跑道上跑步，相向而行，每隔24秒相遇一次，已知甲跑完一圈用40秒；如果他们同向而行，每隔______秒钟相遇一次．
