防止火灾爆炸事故发生的基本原则是＿。

A.防止限制易燃易爆系统的形成

B.防止可燃物外溢泄漏

C.消除各类点火源

D.通风置换

 Without facts , a person can’t form a correct opinion , for he needs to have actual knowledge _____ his thinking .

A．which to be based on

B．on which to base

C．which to be based

D．which to base