m阶B树的根结点至多有______棵子树。
参考答案：m
The girl ____ a beautiful skirt has told me the news. Which is not right?
A．wearing
B．dressed in
C．in
D．having on
手动弯管机可弯制（）以下直径的管子。
A、18mm
B、28mm
C、38mm
D、48mm
