1.My brother is not good at playing tennis.
→My brother doesn't play tennis well
2.Stop talking or you won’t understand the lesson.
→If you stop talking, you will understand the lesson
3.I’ll be on vacation next week, so I won’t be able to attend the meeting.
→Since I'll be on vacation next week, i won't able to attend the meeting
4.Let’s use banana leaves to wrap food.?
→What about using bananas leaves to wrap food?
5.You should have your hair cut.
→I suggest you should have your hair cut