………THEN WHAT I KNOW TODAY,I WOULD HAVE SAVED MYSELF A LOT OF TIME AN...

4- - BAI TAP TRAC NGHIEM CAU DIEU KIEN
BAI TAP TRAC NGHIEM CAU DIEU KIEN

4-

………

then what I know today,I would have saved myself a lot of time and trouble over

the years.

A-had I known

B-did I knowC-If I know

D- If I would know