电缆施工需要的图纸有电缆平面布点置图、电缆排列断面图和（）
参考答案：电缆清册
Parents often have their children_____ little housework so that they can have more time______.
A．doing; studying
B．done; studied
C．to do; to study
D．do; to study
何谓水文效应？
