卷材防水层不得有渗漏或积水现象。()
参考答案:对
We had to _____ our discussion because one of us suddenly got ill. [ ]
A. take off
B. turn off
C. break off
有地球上的“白色沙漠”和“风库”之称的地区是
A.南极地区
B.北极地区
C.西伯利亚高原区
D.撒哈拉沙漠区