may,can,must,need,shall辨析

may,can,must,need,shall辨析
1.-There's somebody at the door.Who ＿＿＿it be?Is it the postman
-No,it ＿＿＿be him.It's just seven o'clock.It's too early
A.may;can't B.will;won't C.may mustn't D.must;may not
2.-Shall I tell John about it
-No ,you ＿＿.I've told him already .
A mustn't B needn't C can't D shan't