tolong dibantu nmr 1-5 ya... makasih:)

1.- shall we spend our holiday in Bali?
- why don't we spend our holiday in Bali?
2.- shall we study English together?
-why don't we study English together?
3.- shall we invite Mr. alex to the party night?
-why don't we invite Mr. alex to the party night?
4. -shall we join the writing competition next month?
-why don't we join the writting competition next month?
5.-shall attend the meeting with Anita?
-why don't we attend the meeting with Anita