He raised his gun, pointed it at a bear and _____aim, shot at it.

A．took careful

B．taking careful

C．to take careful

D．taken careful

教材精典语句理解：请用一句话表达你读了下面这句话后的感受。

花和人都会遇到各种各样的不幸，但是生命的长河是无止境的。

这句话告诉我们：___________________________________________。