我国内河采用的公制水尺，用阿拉伯字表示吃水数值，计量单位是（）
A.mm
B.cm
C.dm
D.m
参考答案：D
It rained a lot during their journey, so they _____ have had a good time. [ ]
A. can't
B. must
C. shouldn't
D. might
发电机运行中失去励磁对发电机有什么影响？
