catch on 受欢迎；流行起来；变得时髦

He invented a new game, but it never really caught on.

他发明了一种新的游戏，但从未真正流行起来。

The idea has been around for ages without catching on.

这个观点已经提出来有年头了，可是一直没被广泛接受。

catch on (to sth) 理解

It took me a blue moon to catch on to the directions.

我花了很久才弄明白说明书的意思。

He is very quick to catch on to things.

他领悟能力很强。

catch sb out

1、使突陷困境

investors were caught out by the fall in share prices.

许多投资者由于股价下跌而突然陷入困境。

2、抓住某人的短处；指出无知；指出过失

Detectives followed him for months hoping to catch him out in some deception.

侦探们跟踪了他几个月，希望能当场抓住他行骗。

They tried to catch her out with a difficult question.

他们试图用一道难题难倒她。

catch up on sth

1、补做（未做的事）；赶做；补上

I have a lot of work to catch up on.

我有许多工作要补做。

No matter hard I try I cannot seem to catch up on all the bills

无论怎么努力，我好像就是无法付清所有的账单。

2、了解（已发生的事情）

We spent the evening catching up on each others news.

我们那一晚上都一直在彼此通报情况。

Im I cant catch up on how things are in that region.

恐怕我不能及时得到关于那个地区情况的消息。

be/get caught up in sth 被卷入；陷入

Innocent passers-by got caught up in the riots.

无辜的过路人被卷入了那场暴乱。

catch up (with sb) | catch sb up

1、赶上，追上（某人）

Go on ahead. Ill catch up with you.

你先走，我随后赶上你。

Ill catch you up.

我会追上你的。

2、赶上，达到（某水平）

missing a term through illness he had to work hard to catch up with the others.

他因病休学一学期，不得不努力学习好赶上别的同学。

catch up with sb

1、产生（曾设法避免的）问题

She was terrified that one day her past problems catch up with her.

她十分害怕过去的问题总有一天又会来困扰她。

2、终于查到某人头上

The law caught up with him years later he had moved to Spain.

多年后当他已移居西班牙时最终还是受到法律的制裁。