modal verbs

must

When a situation is absolutely necessary, the modal verb “must” is a good choice. 

 

must

The main verb that follows “must” is in the simple form. 

must + main verb 

Singular

I must go. 

You must go. 

He must go.  

She must go. 

It must go.  

Plural

We must go. 

You must go. 

They must go. 

go/ went / gone / going

man, hurry up, going to work-2798961.jpg
  • He must go to work today. 
  • He must leave early to get there on time. 
  • Everyone at work must try to work together to accomplish their goals. 

a. Use "must" for things that are necessary.

This is a very strong modal verb. When you use “must,” the situation is very serious or very necessary. 

  • We must obey the law. 
  • Everyone must follow the rules. 
  • Students must arrive at school on time. (They have to* arrive on time.)
  • Teachers must help their students learn. 
  • Drivers must pay attention when they drive their cars. 
  • Parents must take good care of their children. 
  • People must cooperate with each other to get things done. 
  • We must do a better job of taking care of the environment. 
  • We must do everything we can to help endangered species of animals. 

*Note: A popular substitute for “must” is “have to.” In fact, in many circumstances, “have to” is preferred. 

Close-Up of Two Polar Bears on Rocky Terrain
  • We all must do a better job of taking care of the planet. 
Police officer writing a ticket to a car in a sunny parking lot with a colleague in the background.
  • You must obey the law. If you don’t, you might get in trouble. You might even get a ticket!  

B. Use "must" when you believe something is true.

From your point of view, something seems to be true. This is a supposition. In this case, you can choose to use “must.” 

  • A person who has not slept all night must be tired. 
  • Anyone who hasn’t eaten all day must want food. 
  • You must want to learn English if you are on this website. 
  • That man must be unhappy about something. He’s frowning. ☹️
  • The parents of the couple getting married must be very happy and excited today.  
  • The plane must have arrived by now. The arrival was scheduled for 1:30 and it’s now 2:00.  
  • The people of that country must be very upset to have such a stupid leader in charge. 
Happy Vietnamese couple celebrates their wedding with friends in traditional attire outdoors.

They must be very happy. 

C. To form the negative, use "must" + "not."

Note that the negative form is usually left uncontracted–must not. In some parts of the world, as in the United States, the contraction “mustn’t” is not very popular. 

  • You must not go in there. It’s too dangerous. 
  • We must not take unnecessary risks. 
  • People in combat must not try to harm civilians (or noncombatants.)
  • You must not like your job if you complain about it all the time.  (This is a supposition. It might not be true, but there’s a lot of evidence to indicate it is true.) 
  • She mustn’t feel well. (must + not = mustn’t) 
  • It must not get very cold in that part of the world if it is near the equator. 

You must not let that baby go too far. There’s a stairway nearby. 

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