Conjugation
I have just saw at my textbook sentence "어제는 영화를 보았으며 내일은 연극을 볼 것이다." I thought that while conjugate 보다 it should be actually '봤으며" So my question is if this sentence is correct?

Question

Answer

봤으며 is just a contraction of 보았으며.
해요 is a contraction of 하여요.
etc

While these are contractions, they are extremely common and predominantly used and are not by any means informal.

Answer

There is long and short form of several conjugations. Both are correct.