must be 和was的区别？
must跟must be的区别为：含义不同、用法不同、侧重点不同
一、含义不同
1、must
释义：modal（表示必要或很重要）必须。
例句：
In order to take that job，you must have left another job.
为得到那份工作，你肯定已辞去了另一份工作。
2、must be
释义：一定是；必须；准是。
例句：
We must be patient with children.我们对孩子要有耐心。
二、用法不同
1、must
用法：指因需要、命令或强制而必得做某事，侧重于主观上的“必须”。
2、must be
用法：must be是表示被动，用来表示推测。
三、侧重点不同
1、must
解析：must后面只能跟动词。
2、must be
解析：must be后面跟名词或形容词，或者宾语从句。
mustnotbe和cannotbe的用法区别？
The book must be leo , because he like reading books can noe be 的用法 表示不可能准确的判断 must be 是表示一定的意思
must be do和be must do的区别？
must be do 是不存在的。要么must do sth,或must be....(表示一般情况或状态）
must be doing ...肯定正在做....(表示现在正在....)
must和mustbe什么区别，怎么用？
①含义不同
must
释义：（表示必要或很重要）必须。
例句：In order to take that job，you must have left another job.
为得到那份工作，你肯定已辞去了另一份工作。
must be
释义：一定是；必须；准是。
例句：We must be patient with children.我们对孩子要有耐心。
②用法不同
must
用法：指因需要、命令或强制而必得做某事，侧重于主观上的“必须”。
must be
用法：must be是表示被动，用来表示推测。
③侧重点不同
must后面只能跟动词。
must be后面跟名词或形容词，或者宾语从句。
mustbe和couldbe的区别？
can be和could be是时态的差别，有时候could be表语气的委婉。
must be是肯定的推测，can't be是否定的推测，还有may be， might be等都可以表推测
1. can只有两种时态, 即can 和could, 而be able to 有多种时态, 如:was/were able to, will/shall be able to, have/has been able to等:
I’ll be able to drive the car in a week.
Through his diligent work, the deaf-mute has been able to read and write in a sign language.
2．表示过去通过努力终于做成了某事要用be able to，而不能用can。
如：
I was able to swim to the bank after the boat turned over.
can 和be able to 都可以表示能力.can泛指一般的能力,而且只有两种形式,即:can, could．be able to 则主要指具体做到了某件事的能力，其形式主要是靠be 发生变化，所以形式比can 多．
可以说：I can swim. I am able to swim. 但是不能说：All the people could escape from the big fire in time.
只能说：All the people were able to escape from the fire in time.
3．can能表猜测，be able to不能。can的这种用法主要用于疑问句和否定句。
Somebody is knocking at the door. Who can it be?
It can’t be our teacher who is knocking at the door.
其肯定形式是must be。如:
It must be our teacher who is knocking at the door.
must have done something 表示对现在完成或过去动作的猜测，其否定形式是can’t have done。如:
“His parents must have gone abroad.” “No, I don’t think so. They can’t have gone, for I saw them only this morning.”
要特别注意它们的反意问句形式：
He must be a good teacher，mustn’t /isn’t he？
The students must have gone to bed, haven’t they?
They must have finished their lessons yesterday, didn’t they?
could既可以用肯定形式，又可以用疑问或否定形式。如果用could表示现在“可能”，比can语气更加委婉。如：
If you don’t spend enough time on your studies, you could fail in the final examination.
It could be our teacher who turned off the light last night.
与It must be our teacher. 相比,这句话表示的可能性更小, 因为它表示了两种可能性, 既 “可能是”也可能“不是”，而 must be 只表示了一种猜测。
could have done 这个句型有它的特殊含意，表示“本来可能做到而未做到的事”。如：
Our class team could have won the game.
再如：
He cannot be over praised for what he has done for all of us.
