Must/Have To/Have Got To

Must and have to both express necessity:

–You must fill out this form.
–You have to pick up Mr. Roberts.

In some situations, must is more urgent or stronger than have to:

–You must be here for your appointment on time. I have a busy schedule today.
–You have to take another course next year.

The expression have got to is similar in meaning to must and have to but is reserved for spoken English:

–I have got to study more. (i.e., I must study more.)

Examples of Expressing Necessity

• To Washington. I've got to do some research there. I know nothing about the city.
• Hmmm.... I concur with your dentist. The tooth has to come out.