When I called at his home the other day, I found him sitting on an armchair, _____ in his hands. [      ]

A. buried his head

B. burying his head

C. his head burying

D. his head to be buried

油品具有易燃性，是因为（）。

A.油品的热值非常高

B.点燃油品及其蒸气所需要的能量很小

C.油品的闪点低

D.油品的自燃点低