《进口废物批准证书》实行“非一批一证”制度。 ( )
参考答案:对
He _______ Shanghai, for I saw him talking with the headmaster a moment ago.
A.must have gone to
B.can’t have gone to
C.mustn’t have been to
D.can’t have been to
压力控制器可以把不同的信号变成标准的()的输出信号,送给指示或执行机构。
A、0~1.5MPA
B、0.02~0.25MPA
C、0~0.6MPA
D、0.02~1.5MPA