Materi Kelas XI

Expressing Necessity and Obligation

Sample sentences from the article:
Each of us has to finish two thick books….
…he was expected to complete…

Have to / Has to / Had to
Be expected to

These words express necessity or obligation. They usually indicate that someone else has imposed conditions on us. For example:

     I have to take out the garbage. (It’s something I must do now. My mother told me to do it.)
     I am expected to take out the garbage. (It’s a regular responsibility, a daily chore that my parents have        given me.)

A related expression is be supposed to.

     I am supposed to clean my room. (I’m required to do it.)

In the negative, these expressions have different meanings. For example:

     I don’t have to go to the dance this weekend. (There is no obligation. I can choose to go or not.)
     I’m not expected to go to the dance this weekend. (There is no expectation. People will be surprised if I      do go.)
     I’m not supposed to go to the dance this weekend. (I’m prohibited from going. It would probably be            rude for me to go.)

Note:

Must is often used to indicate 'personal' obligation, what you think yourself or other people/things must do. The obligation comes from outside (a rule or law).
Have to or need to are often used to indicate necessity (but not always).   It means doesn't come from a rule or law.
Here are the expressions to show necessity and obligation :

 - It is necessary for you to be here on time.

 - You must finish your reports before the boss ask you.

 - We don't need to come to the party, I think.
 - You have to submit the report by June 2 nd
 - We must be here before the teacher comes

 - The school must provide more sports facilities. 

 - You have to clean the keyboard regularly.
 - I really must get some exercise.  
 - People must try to be more tolerant of each other.
 - If you own a car, you have to pay an annual road tax.