——Have you finished your homework yet?——No, not yet. I think it'll take me __________ half an hour.
A:another
B:other
C:others
D:the other
受凉感冒时,感到呼吸困难的主要原因是( )
如图是电磁继电器的构造和工作电路示意图,要使它的电磁铁对衔铁的吸引力大些,以下做法可行的是( )