膈肌麻痹时，膈肌位置的改变是下列哪一种（）
A.两侧膈肌升高
B.两侧膈肌降低
C.单侧膈升高
D.单侧膈肌降低
E.膈肌局限性隆凸
参考答案：C
We were all surprised when he made it clear that he ____ office soon.[ ]
A. leaves
B. would leave
C. will leave
D. had left
采用减压回路，可获得支系统比主系统低的稳定压力。
