在装卸搬运过程中巧妙利用货物本身的重量和落差原理，或利用滑板、滑槽等来搬运物品时，可称为（）。

A.提高搬运活性

B.省力化原则

C.消除无效搬运

D.人性化原则

No worker and no engineer           who it is that is           for the explosion of the chemical factory.

A．know; to blame

B．would know; blamed

C．know; to be blamed

D．knows; to blame