海关是我国的进出国境监督管理机关。()
参考答案：错
The rescuing soldiers in the helicopters ______ to land on that earthquakestricken area, but failed again
and again.[ ]
A．pretended
B．succeeded
C．managed
D．attempted
为什么大容量机组高、中、低压缸均采用双层缸？
