木材的单位体积的质量称为（）。
A.比重
B.密度
C.重量
D.容积
参考答案：B
He had no idea of what he should say in answer to the question, ______?
[ ]
A. did he
B. should he
C. didn't he
D. shouldn't he
架空敷设步骤为，预制和埋设支架，做好起吊管道前的准备工作，吊装管道、管道接口（）、和接口收尾。
A.质量检查
B.除锈
C.保温
D.试压
