请写出原因
问题描述：
请写出原因
1.Dave _____a letter from his friend in America yesterday.
A.get B.has got C.received D.accepted
2.You_____hand it in at once,you may hand it in tomorrow.
A.needn't B.may not C.can't D.must not
答
1.--------C.received -------收到
2.-------A.needn't ------不必