晶闸管调速系统由()部分组成。
A、三
B、四
C、二
D、五
参考答案:B
The poem did not have an appropriate ending, _________ she would have won the competition.
A.because
B.or
C.but
D.and
新疆适合发展农业的地区是( )
A.砾石戈壁
B.绿洲
C.河流
D.沙漠