27. We/ go/ skiing yesterday.
⇒ We went skiing yesterday.
28. Last week/ we/ study/ how/ surf. It/ be/ very interesting.
⇒ Last week, we studied how to surf. It was very interesting.
29. I/ not play/ badminton last Sunday/ because I/ be/ ill.
⇒ I didn't play badminton last Sunday because I was ill.
30. Where/ be/ the children yesterday morning? They/ be/ at the swimming pool.
⇒ .Where were the children been yesterday morning?They were at the swimming pool.