整流柜的作用是为电解制氢装置提供（）。
A.控制信号；
B.交流电源；
C.直流电源；
D.恒流电源。
参考答案：C
It is reported that 1.4 million people took part in ________ post-graduate entrance exam, ________ 13 percent increase from last year.
A．a; the
B．the; a
C．a; /
D．/; a
世界上使用范围最广的语言是______．
