蝗虫的发育不需经过的时期是 [ ]
A．成虫
B．蛹
C．卵
D．幼虫
答案：B
I spent the whole day repairing the motorbike. The work was ____ simple. [ ]
A. nothing but
B. anything but
C. something of
D. all except
采暖管道必须穿过防火墙时，应采取（）措施。
A.固定、封堵
B.绝缘
C.保温
D.加套管
