《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
He _______ Shanghai, for I saw him talking with the headmaster a moment ago.