原式=2+1-3+2
=2.
故答案为:2.
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A.Never mind
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导致风湿性二尖瓣狭窄患者死亡的最常见并发症是
A.脑血栓
B.心房纤颤
C.充血性心力衰竭
D.亚急性感染性心内膜炎
E.急性肺水肿