题目内容：

英语问题,一定要说明理由!
1.If these trousers are too long,buy a smaller _____
a.set b.one c.piece d.pair
2.Look!an old man is coming.Is that Mr.Smith
It ____ be Mr.Smith.He has gone to Japan
a.must b.can
3.________they______their daughter was at home.they were all in hospital
a.Either...or b.Neither...nor
4.Nancy,would you please turn down the music?Your father is writing his report.
__________.
a.Yes,please b.Sorry.I'll do it right away
c.Sorry.i wont't do it again d.No.I never do it again