缺乏勇气用英语可以说作 "lack of courage"。这个短语来源于古英语中的 "corage"，意思是"胆量、勇气、胆敢"。例句如下：

She lacked the courage to speak out against the injustice.

她缺乏勇气去反对这种不公正。

He didn't have the courage to ask her to marry him.

他没有勇气向她求婚。

The team showed a lack of courage in the face of adversity.

面对困难，球队显得缺乏勇气。

She has always been known for her courage and determination.

她一直以勇气和决心闻名。

He showed great courage in the face of danger.

他在危险面前表现出了伟大的勇气。