Wah How to "Make Request" in many ways.

You can use would like, want or must ask to make request in several ways.

1. We use would like to request in the polite way.
    I would like you to stop smoking.
    Dad, You smoke too much. I would like you to quit smoking.
    You are a grate instructor, I would like you to come back sometimes.
    It's very urgent but I would like to have a word with you.

2. We use want to request in the neutral way.
    I want you to stop smoking.
    I want you to study for examination tomorrow.
    I do not want her to be careless.
    We want Mariana to do this project.

3. We use must ask to request in the angry way.
    I won't put up with it any longer, I must ask you to stop smoking now. 
    I must ask you to stay away from me. You are very annoying.
    You always do mistake, I must ask you to consider yourself.
    You are always late for work, I must ask you to resign from this job.

'I want you to not smoke in here.'

Wah How to use "Must and Have to"

Affirmative	Negative	Interrogative
I have to go.	I don't have to go.	Do you have to go?
He has to go.	He doesn't have to go.	Does she have to go?
I must go	I must not go.	Must you go?
He must go.	He mustn't go.	Must she go?

1. We use must or have to to express a strong obligation or necessity base on the rule,an authority or circumstances.
    I have to tell you that I love you. = I must tell you that I love you.
    She has to clean up this room. = She must clean up this room.
    It is close to seven o'clock. We have to go to school.
    The traffic is very bad, we have to take the subway instead.

2. We can also use must or have to with the idea of deduction when we are sure something is true from some evidence or reason.
(More example here: Wah How to use "Must/Might/May/Can't be")
    This meal has to be delicious.
    Mark is a English teacher, he must know a lot of English grammars.

3. Have to can be used in the past or the future.
    Yesterday,I had to work all day. I musted work all day is incorrect.
    Did he have to go to school on last Saturday.
    We will have to get up early.
    Will I have to speak with her?

Wah How to use "Must/Might/May/Can't be"

When you are sure something is true, you can say "must be". 
        He is speaking Japanese, He must be Japanese. (I am sure he is Japanese.)
        She must be a police officer.(I think she is a police officer.)
        This must be the way to the park. (I am certain this is the way to the park.)

If you are quite sure something may be true, you can say "may/might be".
        He is so late at the meeting, the traffic might be bad.
        John is not at the office now, he may be taking the day off.
        I am not sure but she might be older than me.

And If you want to say something you think it is unlikely, you can say "can't be".
        He is very old, he can't be the student.
        Sarah is at the hospital, she can't be working today.
        This restaurant is very delicious, it can't be going out of business.

Kenny Chesney - Must Be Something I Missed
"There must be something I missed
I wake up in the morning just making a fist
I don't call it living, I just exist
There must be something I missed..."

Wah How to use "Need"

Need is used when you want to say something necessary to do or to have.
I need to do it = I must do it.

Affirmative           
     I need to go now. (It's necessary to go now.)

Negative
     Today is Saturday, I don't need to go to school. 
     or I needn't go to school.

Interrogative
      Does she need to have the description for buying medicine?  
     or Need she have the description for buying medicine? 

The modal use of 'need' is restricted to its present tense-form. To refer to the past you have to use..

Wah How to use "Should"

Should is a modal auxiliary verb. It is used to express the speaker’s opinion at the moment of speaking

Affirmative           

• I should go.
• He should go.

Negative

• I shouldn't go.
• He shouldn't go.

Interrogative

• *Should I go?
• Should he go?

*Questions with Should I / we …?  are unusual.We usually say..