以下用适当的情态动词填空
1.nobody___livewithoutairandwater
2.-___hespeakchinese?YES,alittle
3.thebook____bereturnedbeforesaturday
4.you___giveupsmokingatonce.it'sbadforyourhealth
5.Excuseme.___iaskyouaquestion?
6.thetrainwillleaveathalfpastsix,soi__gettherefifteenminutes,earlier
7.youdon't____worryabouther.sheismuchbetternow.
8.ifyouwanttopasstheexam,you___workharder