建筑工程广泛使用（）作为混凝土的早强剂。
A.亚硝酸钠
B.氨水
C.还氧树脂
D.丙酮
参考答案：A
The _____ of his clothes indicated too clearly that he had been playing football.
A．state
B．condition
C．occasion
D．situation
根据利尿药的效应力大小，可分为几类？举例说明每类的作用部位及机制。
