允许在堤防管理内（）。
A.挖塘
B.取土
C.打井
D.维修养护施工
参考答案：D
某路公共汽车10分钟一辆，甲、乙两个人独自等车，求“两人等车时间的差不超过3分钟”的概率．
Prototyping method is a dynamic design process, it requires people who use prototyping method should have the following capability( ).
A．proficient program expertise
B．immediately acquire requirement
C．coordinate & organize eloquently
D．handle tools smartly
