汽轮机按热力特性可以划分为( )汽轮机。
A.凝汽式
B.背压式
C.抽汽式
D.多压式
E.塔式
参考答案:A,B,C,D
______ many times, but he still couldn't understand it. [ ]
A. Having been told
B. Though had been told
C. He was told
D. Having told
血管紧张素转化酶抑制剂的主要适应证是()、充血性心力衰竭。