按排土场与露天矿的相对位置，排土场可分为（）和外部排土场。
参考答案：内部
Some people prefer to work and live in Chengdu, for the price of an apartment is less than half of ________ of big cities like Beijing, Shanghai, and Guangzhou.
A．it
B．what
C．that
D．One
风湿性心内膜炎最常累及（）
A.肺动脉瓣
B.三尖瓣
C.主动脉瓣
D.二尖瓣
E.左心房后壁
