underline

画线、加底线

She underlined the key words in red before the exam.

考试前她用红笔在关键字下面画线。

强调、突显、彰显

The accident underlines the need for stricter safety rules.

这起事故凸显了制定更严格安全规范的必要。

底线、下画线

Add an underline to the title to make it stand out.

在标题加上底线，让它更醒目。