血液进入左心室的入口是（）
A.上腔静脉口
B.下腔静脉口
C.冠状窦口
D.左房室口
E.肺静脉口
参考答案：D
8100÷200的商是______，余数是______．
It was ________ your timely help that we accomplished the task on time.[ ]
A．as to
B．thanks to
C．but for
D．ought to
