in a mess 乱作一团，介词in和名词搭配表示状态

in good order 秩序井然

in good health 身体健康

in a good mood 心情好

in a good temper 脾气好

light up 有喜气洋洋，容光焕发的意思 Tom's face lit up when he saw his old friends.

pounce on :

1.向……猛扑 He pounced on the thief.

2.对……大做文章 Don't pounce on his mistake.

They need to be involved in activities.他们要积极参与各类活动。

It gets you to visualize the setting of the story.这能让你对故事场景形象化。