混凝土和砂浆用再生骨料碱集料反应中膨胀率应小于（）%？
A. 0.05
B. 0.10
C. 0.15
D. 0.20
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If the goods shipped are perishable，low cost goods，live animals，deck cargo，etc.，the freight and all related charges shall be paid（）.
A. at the time of shipment
B. on vessel's arrival
C. at the time of sailing
D. at the time the voyage has been accomplished
什么是MSDS（MSDS-Material safety data sheet）？
抽油机碰泵操作中，悬绳器卸载后要确认（）无下滑。
A. 抽油机驴头
B. 光杆
C. 抽油机刹车
D. 抽油机曲柄
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