1. keep up (일정수준) 계속하다.

keep it up keep it up keep doing~ 코치들이 가장좋아하는 표현 (지금 그 속도 수준으로) 계속해 멈추지마

keep it up 그래서 힘내라는 표현도 된다.

you are doing really well keep up the - good work 지금 너무 잘하고 있으니 그대로만해

if you keep up the good habit you can make a batter result 

your habit decides your future 습관이 미래를 결정한다.

keep up + with  따라가다 맞춰가다. keep up with new technology

the world changes so fast so it's hard to keep up with it.

Can you speak a little slowly please so that I can keep up with you.

2. catch up 따라잡다

- let's go

- go (on) ahead! I will catch up with you guys later . 먼저가 따라갈께

Do you have a minute to catch up ? 대화할 시간 있어? (그간 못한 이야기가 있거나 더해야할 이야기가 있을때)

I need to catch up on my work 나 일들을 빨리 처리해야해 (그동안 못해서 남아있는일들을 만회해야해)

I have some work - have to catch up on - here.

I studied more to catch up on my last class.

keep up : 동일선상에서 뒤쳐지기 않기 위해 따라가는것

catch up : 뒤쳐저 있을때 동일선상에 가기위해 따라가는것