YOU SAID:

I can tell you worked hard on preparing

INTO JAPANESE

一生懸命準備したのがわかります

BACK INTO ENGLISH

I can see that you've worked hard to prepare

INTO JAPANESE

一生懸命準備してきたのがわかります

BACK INTO ENGLISH

I can see that you've been working hard to prepare

INTO JAPANESE

一生懸命準備してきたのがわかります

BACK INTO ENGLISH

I can see that you've been working hard to prepare