More info can. can't, have to, don't have to, must and must not

Have to and must are used to indicate a rule or an obligation. They have almost the same meaning. Have to is often used to indicate the obligation comes from outside, eg I have to lose weight (the doctor told me). Must often shows an internal feeling, eg I must call my mother tonight.

Don't have to and must not (mustn't) are very different. Don't have to shows a lack of obligation / no rule eg you don't have to carry your umbrella when it rains (but you can if you want to). Mustn't indicates prohibition, the existence of a rule saying don't, eg you mustn't chew gum in class (if you do there will be some consequence).

Can shows permission, that something is possible or allowed. eg People in England candrink alcohol when they're 18.

	Alternatives	Past tense
must / have to		had to
don't have to	need not (needn't)	didn't have to
mustn't	can't	was not allowed to / couldn't
can	be allowed to	could / was allowed to

Complete the following with have to, don’t have to or mustn't.

You _________________ have a licence to drive a car.
You _________________ have a licence to ride a bicycle.
You _________________ tip waiters and taxi drivers in Japan.
You _________________ wear shoes inside your house in Japan.
Students _______________ go to school on Saturday in Japan.
Students _______________ go to school on Saturday in England.
Foreigners ______________ carry an ID card in Japan.
Policemen ______________ wear a uniform.
Passengers ________________ smoke on the subway.
Gardeners _______________ wear ties.

Taken from: http://english-the-international-language.com/rules.html

HAVE TO and DON'T HAVE TO

HAVE TO

Have to / Has to = it is necessary 
Don't have to / Doesn't have to = it isn't necessary

AFFIRMATIVE SENTENCES	SUBJECT	MODAL	VERB	EXAMPLES
affirmative sentences ( + )NECESSITY:  have to/has to  means it is necessary.	I you we they	have to	clean get pick up have eat go work	I have to clean my room. You have to get a new book. We have to pick up the laundry. They have to have a notebook.
	he she it	has to		He has to eat dinner now. She has to go to work now. It has to work.
NEGATIVE SENTENCES	SUBJECT	MODAL	VERB	EXAMPLES
negative sentences ( - )LACK OF NECESSITY:  don't have to/doesn't have to  means it is not necessary.  You have a choice.	I you we they	don't have to	work do clean eat work go be	I don't have to work on Saturday. You don't have to do that. We don't have to clean the car. They don't have to eat pizza.
	he she it	doesn't have to		He doesn't have to work tomorrow. She doesn't have to go today. It doesn't have to be that way.
QUESTIONS	DO	SUBJECT	MODAL	VERB	EXAMPLES
questions ( ? )	Do	I you we they	have to	clean get pick up have eat go work	Do I have to clean my room? Do you have to get a new book? Do we have to pick up the laundry? Do they have to have a notebook?
	Does	he she it			Does he have to eat dinner now? Does she have to go to work now? Does it have to work?

Section A:  Pizza!
1. When you make pizza, you ___ have some pizza sauce.	have to has to don't have to doesn't have to
2. You also ___ have some cheese on top of the pizza.	have to has to don't have to doesn't have to
3. You ___ have peppers on your pizza, but you can if you want to.	have to has to don't have to doesn't have to
4. A good pizza ___  taste good.	have to has to don't have to doesn't have to
5. So, you ___ choose the pizza toppings that you like best.	have to has to don't have to doesn't have to
6. Personally, I love tomatoes, so I always  ___ have tomatoes on my pizza!	have to has to don't have to doesn't have to
7. You ___ make your own pizza, you can buy a pizza from a pizza shop if you want to.	have to has to don't have to doesn't have to
8. Pizza tastes best when it's hot, but you ___ eat hot pizza. You can eat it cold too.	have to has to don't have to doesn't have to

 

Section B:  Help Wanted: Help Wanted: Secretary. No experience necessary. Must type 50 words per minute. Work Monday-Friday, weekends off. Answer phones, use computer, file reports. Read the advertisement, then choose the correct words below.
9. The secretary ___ know how to type.	have to has to don't have to doesn't have to
10. A secretary ___  be a woman. The secretary can be a man.	have to has to don't have to doesn't have to
11. ___ the secretary ___ work Saturdays?	Do / have to Does / have to Do / has to Does / has to
12. No, he/she ___ go to work on saturdays.	have to has to don't have to doesn't have to
13. The secretary also ___ answer the company's phones....	have to has to don't have to doesn't have to
14. ...and he/she ___ file reports every week.	have to has to don't have to doesn't have to
15. ___ the secretary ___ use a computer?	Do / have to Does / have to Do / has to Does / has to
16. Yes, He or she ___ use a computer.	have to has to don't have to doesn't have to

 

Section C:   On Health...
17. People ___ eat food to stay alive.	have to has to don't have to doesn't have to
18. People ___ eat pizza and candy to stay alive. They can choose healthy food.	have to has to don't have to doesn't have to
19. A person ___ drink water to stay alive.	have to has to don't have to doesn't have to
20. A person ___ smoke cigarettes to stay alive.	have to has to don't have to doesn't have to

Taken from: http://www.english-zone.com/verbs/haveto1.html

Preposition of Movement

exercises Will Vs. Might

Modal Verbs (Might & Will)

Might is a modal verb commonly used to express possibility. However, this is not the only use it has, it is also used in conditional sentences, when making suggestions or requests (although this is less common in American English)

Below there are some examples of the different uses of the modal verb MIGHT:

• Your purse might be in the living room. (possibility)
• If I didn't have to work, I might go with you. (conditional)
• You might visit the botanical gardens during your visit. (suggestion)
• Might I borrow your pen? (request)

As you have seen in UNIT 13 of the ELEMENTARY BOOK (CUTTING EDGE) we will focus on the use of MIGHT as a modal verb used to express POSSIBILITY.

Now you will see how MIGHT behaves in different contexts (tenses)

1. Might can be found in positive and negative forms.
2. it can be found in present, past, future
3. it can be substitute with COULD or MAY

EXAMPLES:

1. She might be on the bus I think her car is having problems. In this sentence we can see the use of MIGHT in a positive form in a sentence that makes reference to something that it is happening in the present or moment of speaking..
2. She might not be on the bus. She might be walking home. In this sentence we can see the use of MIGHT in a negative form in a sentence that makes reference to something that it is happening in the present or moment of speaking..
3. She might have taken the bus. I'm not sure how she got to work. In this sentence you can observe that the other verbs (HAVE TAKEN) are found in a present perfect structure, therefore we can determine that the person is referring to something that has already happened. 
4. She might not have taken the bus. She might have walked home.In this sentence you can observe that the other verbs (HAVE TAKEN) are found in a present perfect structure, therefore we can determine that the person is referring to something that has already happened. 
5. She might take the bus to get home. I don't think Bill will be able to give her a ride.In this sentence we find WILL, in this particular case it is working as most people know (the auxiliary of the future tense). Read carefully, the sentence is positive, because in the main sentence the writer is stating that the it could be possible that the woman take the bus. The secondary sentence it's just explaining the reason why.
6. She might not take the bus. She might get a ride from Bill. In here, we can figure out the tense of the sentence only by reading.

NOTE: MIGHT NOT Vs. COULDN'T

MIGHT NOT suggest you don't know if something happens. COULD NOT suggests that it is impossible for something to happen.

Example: Jack might not have the key. (Maybe he doesn't have the key)

Jack could not have the key (It is impossible that he has the key)
Will: we often associate Will with a future auxiliary. However, we have little or no control over what WILL happen in the future, but we can try to judge if an event is likely to occur or not. 

1. I will graduate in 5 years. (if everything goes smooth it is possible I graduate in 5 years)
2. I will travel abroad if I have the money. (It is possible for me to travel if I have enough money)