将695600保留两个有效数字的近似数是 [ ]
A．690000
B．700000
C．6.9×105
D．7.0×105
答案：D
None of the workers attended the party, ?
A．did they
B．did he
C．didn’t he
D．didn’t they
m阶B树的根结点至少有______棵子树。
