( )管壁较厚，适用于潮湿、有机械外力、有轻微腐蚀气体场所的明暗配。
A．焊接钢管 B．电线管 C．硬塑料管 D．半硬塑料管
参考答案：A
They _____ 3000 English words by the end of next month. [ ]
A. learned
B. had learned
C. will learn
D. have learned
《廉政准则》对党员领导干部廉洁从政提出了哪些要求？
