请问英语中couldn't wouldn't needn't mustn't的区别与用法?

请问英语中couldn't wouldn't needn't mustn't的区别与用法? 英语中何时使用wouldn,t have done shouldn,t have done couldn,t have done needn,t have donewouldn have done shouldn have done could have done needn have done 呢 He should have known the police wouldn't allow it but he didn't.He should have known the police wouldn't allow it_______.A.and he did B.but he didn't C.but he couldn't D.but he had新概念英语第二册中65课的题,为什么选择B项呢?如何 the machine wouldn't work.can you try it again为什麽是选wouldn't而不是couldn't ?详情解释. If I were you,I______worry so much.A couldn't B mustn't C needn't D wouldn't请问这道英语单选选哪个呢?请告知为什么选那项,别的为什么不选?最后还请翻译一下这句话.. 请问,wouldn't you怎么读, it couldn,t be better,but iknow,it wouldn,t be any the car___________be OK (修好）A.couldn't B.wouldn't i'm feeling much better now so you Wouldn't the doctor A.Couldn't B.Wouldn't C.Can't D.Needn't 英语选择：What would have happened if you ___ her child 应选什么?为什么?A.hadn't helped B.couldn't help C.wouldn't help D.didn't help You park here!It’s an emergeney exit.A.wouldn’t B.needn’t C.couldn’t D.mustn’t He tried the door very hard,but it ______ openA.couldn’t B.wouldn’t C.shouldn’t The door ______ open,no matter how hard she pushed.A.couldn't B.wouldn't 求解释、分析 请问：I couldn't care less.中的couldn't表示什么意思? If I hadn't practiced when I was young,I____able to play so well now.A wouldn't be B won't be C wouldn't have been D couldn't have been How I wish I ( ) that to him yesterday!what shall I do?A.didn't say B.hadn't said C.wouldn't say D.couldn't say You look so tired ._Last night I___ sleep well .A.couldn't B.wouldn't C.mustn't D.needn't选哪个 i tried to stop him from smoking,but he just __listen.a.won't b.wouldn't c.didn't d.couldn't