什么是缓凝剂？
参考答案：
缓凝剂是可在较长时间内保持混凝土工作性，延缓混凝土凝结和硬化时间的外加剂。
Doris has won the first prize in the speech competition; and she is so excited that she feels ______desire to go to bed．
A．the most
B．more
C．worse
D．the least
消炎、镇痛药
A．舒巴坦 B．布洛芬 C．西替利嗪 D．巯嘌吟 E．尼可刹米
