用情态动词should,may,must,can,could,ought to 填空

用情态动词should,may,must,can,could,ought to 填空
1.We （）buy the more expensive one.It will last much longer.
2.Do you want to get better photos?You （）change it for a big one.
3.I think she （）be at home.I hear she is speaking.
4.（）I have your name,please?
5.（）we（）do it at once?