began后加什么？
began是begin的过去式。begin后要用动词不定式to do.
She began to explain her plan of action to the group.
她开始向小组讲解她的行动计划。
He began to question the ethics of his position.
他开始对他的立场是否符合道德准则提出质疑。
Slowly, an image began to appear on the screen.
屏幕上慢慢地出现了一幅图像。
He took one smell of the liquid and his eyes began to water.
他闻了一下那种液体，就流起泪来了。