(영문법)조동사

A - Can/Could
[예문]

She can speak English, but she can't speak Spanish.
I'm having a party next Friday, but Jane and Kate can't come.
I was tired last night, so I couldn't sleep.
I cannot believe the rumors about you.
Can(/May) I use your cell phone?

[비교] 

Can you speak English? Do you speak English?(보편적)
[비교] 

Can you run this machine?(보편적) Are you able to run this machine?

B - Will/Would
[예문] 

You can call me tonight. I'll be home.
I think that she will pass her driver's test.
He won't take my advice.(cf. He wouldn't take my advice)
Would you have some more coffee?
I thought he would do it.
I'll call you tomorrow, OK?

[비교]

I'm going to buy some books tomorrow. (예정된 미래)
       I'll buy some books tomorrow.
[비교]

He used to go to the theater very often.(과거의 규칙적 습관: 지금은 “아니다”의 뜻)
He would go to the theater very often.

[주의]

This machine is used to take a picture. (이 기계는 사진 촬영에 사용된다.)
She is used to playing the piano. (피아노 연주에 익숙하다)
She used to play the piano when she was young.(피아노를 연주하곤 했다.)

C - May/Might
[예문]

I might(/may) go to the movies tonight.
He may know the truth about the news.(현재 사실에 대한 불확실한 추측)
=> Perhaps(/Maybe) he knows the truth about the news.
He may have seen the lady at the party last Saturday.(과거 사실에 대한 불확실한 추측)
You may go outside after dinner. Excuse me, May I smoke here?

You may well hate me.(~~하는 것도 당연하다)
= It is natural that you should hate me.
You may as well finish your home work right now.(~~하는 것이 더 낫다)
= You had better finish your homework right now.

D - Shall/Should
[예문]

It's a good movie. You should go and see it.
I should(/ought to) study English tonight, but I think I'll go to the movies.
You shouldn't go to bed so late. You shouldn't watch TV so much.
It's too late. I think I should go home now.
Should I buy something special for dinner?
My father proposed that I (should) find a new job as soon as possible.

It + be동사

necessary, important, proper, fair, natural good, rational, right, well, no wonder, imperative, essential, advisable,  urgent (이성적 판단의 형용사)

that 주어 + (should) + 동사원형

[예문]

It is natural that he (should) be mad at his girl friend.
It is necessary that you (should) take care of your brothers.

주어 +

insist, demand, require, request, desire, wish, order, command, decide, ask, suggest, propose

that 주어 + (should) + 동사원형

[예문]

He suggested that all the employees (should) attend the manager's farewell party. 

It + be 동사	strange, curious, odd, wonderful,  surprising, regrettable, a pity, etc	that 주어 should + 동사원형 (~~하다) 판단의 근거
주어(사람) + be동사	surprised, shocked, embarrassed, amazed, stunned, astonished, sorry, etc	that 주어 should have P.P  (~~했다니)

[예문]

It is strange that he should not understand the problem.

I'm surprised that he should have talked to me like this.

E - Must/Have to
[예문]

My friends have the same zip code as you. They must live close to you.
I'm sorry. I must have the wrong number.
Workers must(/have to) wear safety glasses in front of this machine.
You must not be late for school again!

You must not dance with me at the party. (~~할 필요는 없다)
= You don't need to dance with me at the party.
= You need not dance with me at the party.

	불확실한 추측	확신	강한 부정
해석	~~일지도 모른다	틀림없이 ~이다	~~일 리가 없다
현재사실	He may know that	He must know that	He cannot know that
과거사실	He may have known that	He must have known that	He cannot have known that.

[조동사 + have + 과거분사]의 해석
1. should have 과거분사 (~~했어야 했는데: 과거 사실에 대한 후회나 비난)
2. ought have 과거분사 (~~했어야 했는데: 틀림없이 ~~일 것이다 의 뜻)
3. need not have 과거분사 (~~할 필요가 없었는데)
4. would rather have 과거분사 (= had better have 과거분사: ~~하는 편이 좋았는데)
5. would have 과거분사 (~~했을 텐데)
6. could have 과거분사 (~~할 수 있었는데)