大旨

liǎo jiě dà zhǐ

了解大旨

get the gist

jiū qí dà zhǐ

究其大旨

explore the central idea

nǐ yào xiān què dìng wén zhāng de dà zhǐ

你要先确定文章的大旨。

You have to determine the main idea of the article first.