Hello

Hi, how are you? 

I guess you guys are studying hard.  (Note:  Often used in colloq. speech, "you guys" can include girls.  Just don't use it when you need to be formal or polite)

Studying is very exciting.  I study hard for my exams.

Hmm, today will be a strange day... maybe.  (I like that better than following with "I don't know", but that's my style :P)

I hope you have a goooooooooood day!!

Hello

Hi, how are you?
I guess you guys are studying hard.
Study something is very exciting work, and I study hard for my exams.
Hm, today will be a strange day....
I don't know.
I hope you have good day!

감사합니다.