1) Pattern Talk

I didn't know you were such a + 명사.
네가 그렇게 대단한 ~인 줄은 몰랐어.

I didn't know you were such a techie.
네가 그렇게 대단한 컴퓨터 전문가인 줄은 몰랐어.

I didn't know you were such a pianist.
네가 그렇게 대단한 피아니스트인 줄은 몰랐어.

I didn't know you were such a comedian.
네가 그렇게 대단한 코미디언인 줄은 몰랐어.

I didn't know you were such a sports person.
네가 그렇게 대단한 운동선수인 줄은 몰랐어.

I didn't know you were such a peny pincher.
네가 그렇게 대단한 구두쇠인 줄은 몰랐어.

2) Role Play

A  :  Connect the thingy to the doohickey.
이걸 저기에 연결해 봐.

B  :  I didn't know you were such a techie.
네가 이렇게 대단한 컴퓨터 전문가인 줄은 몰랐어.

: I know my stuff.
이쪽은 내가 선수지.