几道英语选择,需要原因1.---Frank isn't in the house now.---____ left by

几道英语选择,需要原因
1.---Frank isn't in the house now.
---____ left by the back door?
A.Had he B.Must he have C.Should he have D.Could he have
2.I'm sorry ,but I must say his English still___.
A.need to be improved B.needs to improve C.needs to be improving D.needs improving
3.You'll like rhe new school.It ___ be a little small,I think ,but you'll get used to it soon.
A.could B.must C.shall D.should
4.When three pwople travel with me,there____ someone who ____be my teacher.
A.must have ,might B.must be,can C.may be,could D.may have ,may
麻烦说明原因