If you try to sit on two chairs, you will fall             them For life, you must choose one chair. [ ]

A. between

B. under

C. among

D. into

不属于安全事故处理原则的是( )。

A．事故原因未查清不放过

B．有关人员未受到教育不放过

C．“三同时”原则

D．“四不放过”原则