Need to / Have to

Need is a semi-modal verb because in some ways it is like a modal verb and in other ways like a main verb.

We use need mostly in the negative form to indicate that there is no obligation or necessity to do something:

You needn’t take off your shoes.

 

Need: form

Affirmative form

Affirmatives with the semi-modal need are not common and they are used in formal contexts. There is almost always a negative word (e.g. no one, nobody, nothing) or phrase in the clause, even if the verb phrase is affirmative:

No one need think that we are doing this every week. (we are not doing this every week)

Nobody need know the name of the person who made the complaint.

Not a thing need change on this page.

Need comes first in the verb phrase (after the subject and before another verb):

Let’s forget about it. No one need know about it.

We can’t use another modal verb with need:

No one need read this.

Not: No one need must read this. or No one must need read this.

Negative form

Warning:

We form the negative by adding not after need. Need not can be contracted to needn’t. We don’t use don’t/doesn’t/didn’t with the semi-modal verb need:

You need not spend a lot of money on presents. (formal) (or You needn’t spend a lot of money on presents.)

Not: You don’t need spend a lot of money on presents.

See also:

• Modal verbs
• Semi-modal need and main verb need

Question form

The question form of the semi-modal need is not very common. It is rather formal. The subject and need change position to form questions. We don’t use do/does/did.

Need we write this down?

Not: Do we need write this down?

"Have to" is used to express certainty, necessity, and obligation.

Examples:

• This answer has to be correct. certainty
• The soup has to be stirred continuously to prevent burning. necessity
• They have to leave early. obligation

HAVE TO 

"Have to" behaves quite irregularly in the past and the future. Study the chart below to learn how "have to" behaves in different contexts.

Use	Positive Forms 1. = Present   2. = Past   3. = Future	Negative Forms 1. = Present   2. = Past   3. = Future	Also use:
have to certainty	1. That has to be Jerry. They said he was tall with bright red hair.2. That has to have been the right restaurant. There were no other restaurants on the street. 3. NONE	1. SHIFT TO "MUST" That must not be Jerry. They said he has blond hair, not red hair.2. SHIFT TO "MUST" That must not have been the right restaurant. I guess there was another one around there somewhere. 3. NONE	must, have got to
have to necessity	1. She has to read four books for this literature class.2. She had to finish the first book before the midterm. 3. She will have to finish the other books before the final exam.	1. She doesn't have to read "Grapes of Wrath." It's optional reading for extra credit.2. She didn't have to write a critique of "The Scarlet Letter." She had to give a presentation to her class. 3. She won't have to take any other literature classes. American Literature 101 is the only required course.	must

REMEMBER: "Do not have to" vs. "Must not"  "Do not have to" suggests that someone is not required to do something. "Must not" suggests that you are prohibited from doing something. Examples: You must not eat that. It is forbidden, it is not allowed. You don't have to eat that. You can if you want to, but it is not necessary.

EJERCICIO 

1. Larry  go to the bank. He hasn't got any money.
2. You  smoke in the baby's room.
3. You  pay. The entrance is free.
4. I  hurry up if I don't want to miss the plane.
5. In the company, everybody  start work at 8:30.
6. You  cook tonight. I have already prepared the dinner.
7. I  pick up my sister from the airport tomorrow.
8. She  work. Her husband earns enough money for both of them.
9. You  smoke at the petrol station.
10. If you want to study here, you  pass an entrance examination.

VIDEO

https://www.youtube.com/watch?v=DbwnXRtzQ_E