晶闸管有三个电极,即阳极、阴极和()。
参考答案:控制极
------I’d like to book a round- trip ticket.
------Sorry, sir, but there are no tickets______ at the moment.
A.available
B.usable
C.suitable
D.comfortable
整治浅滩,就是消除浅滩,从而满足该河段设计的航深要求。