水准网包括闭合水准线路和附合水准线路。（）
参考答案：对
—Tom has never visited the Great Hall of the People, _____?
—He went there last month．
A．hasn’t he; No, he hasn’t
B．has Tom; Yes, he has
C．hasn’t Tom; No, he hasn’t
D．has he; Yes, he has
拆汽封块时，若汽封块压下就不能弹起来，怎么处理？
