已知移动通信基站的高频开关电源系统中,安装3个50A整流器,这些整流器是()关系。
A、并联
B、串联
C、混联
D、相互独立
参考答案:A
— Was the driving pleasant when you went to Mexico last summer?
— No, it __ for four days when we arrived, so the roads were very muddy.
A.was raining
B.had been raining
C.would be raining
D.rained
什么是新体诗?新体诗有哪些代表作家?