Ability/Possibility
We have enough milk in the fridge so we (must, mustn't, don't have to) buy some more.
We have enough milk in the fridge so we don't have to buy some more.
A: Someone is knocking at the door.
B: It ___________ be the pizza delivery man. I ordered a pizza.
It must be the pizza delivery man. I ordered a pizza.
She might can join us for dinner if she finishes work early.
She might join us for dinner if she finishes work early.
They are required to wear a uniform.
They must wear a uniform.
They have to wear a uniform
Time is not on our side. We (must, mustn't, don't have to) hurry.
Time is not on our side. We must hurry.
I know you ordered a pizza. But it ___________ be him, because you ordered the pizza five minutes ago.
I know you ordered a pizza. But it can't be him, because you ordered the pizza five minutes ago.
He should attends the meeting on time.
He should attend the meeting on time.
Is it conceivable for her to arrive by noon?
Might she arrive by noon?
Could she arrive by noon?
May she arrive by noon?
Mary gave me a letter to send. I (must, mustn't, don't have) forget to mail it.
Mary gave me a letter to send. I mustn't forget to mail it.
B: Yes, you are right. Then it ___________ be your sister.
B: Yes, you are right. Then it might be your sister.
He must be able finishing the project on time, considering his experience.
He must be able to finish the project on time, considering his experience.
She is outlawed from entering the restricted area.
She mustn't enter the restricted area.
She can't enter the restricted area.
You (must, mustn't, don't have) wash those carrots. They've already been washed.
You don't have to wash those carrots. They've already been washed.
No, it ___________ be my sister, she's out of town.
No, it can't be my sister, she's out of town.
Would you mind to help me with my luggage?
Would you mind helping me with my luggage?
They have the proficiency to solve the complex problem.
They can solve the complex problem.
They are able to solve the complex problem.
He will be having lessons for another two hours. We (must, mustn't, don't have to) visit him now.
He will be having lessons for another two hours. We mustn't visit him now.
Well, then just open the door; it ___________ be important.
Well, then just open the door; it might be important.
You ought to not be so harsh on yourself.
You ought not to be so harsh on yourself.
You are not compelled to attend the optional seminar.
You need not attend the optional seminar.
You don't have to attend the optional seminar.