瓷砖在铺贴的过程中，必须留缝，填缝一般在贴砖铺贴（）小时后，太早可能会造成瓷砖高低不平或者松动脱落。
A.12
B.8
C.24
D.42
参考答案：C
— Isn’t it hard to drive downtown to work?
— Yes, that’s why I to work by train.
A．have been going
B．was going
C．have gone
D．will have gone
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