管道安装前应认真核对元件的（）和质量证明文件等。
A.规格
B.型号
C.材质
D.外观质量
E.光谱检测报告
参考答案：A, B, C, D
I'm very sorry to keep you _ so long. I have something important to do. [ ]
A. wait
B. waiting
C. waiting for
D. waited
—Some wine ?
—Thank you ________.I have to drive home.
A．With pleasure
B．That would be nice
C．I would rather not
D．Just what I needed.
