矿石批重越大，愈加重中心，批重越小，愈加重边缘。
参考答案：对
Had I run out of gas, I ought to have called the garage.
A．had
B．would have
C．would
D．should have
在一棵二叉树上第5层的结点数最多是( )。
A．8
B．16
C．32
D．15
