下列哪项引起左室压力负荷过重（）。
A.高血压
B.二尖瓣关闭不全
C.主动脉瓣关闭不全
D.甲状腺功能亢进
E.贫血
参考答案：A
Could you tell me when _____? [ ]
A. does the train leave
B. will the train leave
C. the train has left
D. the train leaves
