二尖瓣狭窄合并肺动脉瓣关闭不全时有()
A.左室后负荷增加
B.左室前、后负荷均增加
C.右室前、后负荷均增加
D.左、右心室前负荷均增加
E.右室前负荷增加
参考答案:C
Sam enjoys ______ stamps. And now he has 226 of them. [ ]
A. to collect
B. collected
C. collects
D. collecting
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