He worked hard _ he passed the exam. [ ]
A. too; to
B. so; that
C. as; as
D. both; and
答案:B
下列因素中能造成循环水pH升高的有()。
A.冷却塔周围空气氨含量高
B.蒸发量小
C.含碱介质的水冷器泄漏
D.补水量大
吃水