生产水泥需加入适量的石膏以调节水泥的凝结速度,石膏的用量要适量,否则过量的石膏会造成水泥()现象。
A.凝结速度过快
B.凝结速度过慢
C.安定性不良
D.前期强度低
参考答案:C
He _______ his gun under the tree where he was __________.
A.lay; laying
B.laid; lying
C.lied; laying
D.lay; lying
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