Page 125 - English Vocabulary In Use upper intermediet and advance

60 Obligation, need, possibility and probability

Obligation

Must is an instruction or command; that is why we see it on notices, e.g.Dogs must be kept
on a lead. Cars must not be parked here.
Have (got) to says that circumstances oblige you to do something. Often, the two meanings
overlap and there will be a choice of how to express the obligation, but not always.

I must get my hair cut! There's no bus service, so I have
[command to yourself] to walk to work. [circumstances]
I've got to get my hair I really must get a bicycle.
cut. I've got an interview [instruction to yourself]
tomorrow. [circumstances]
The company is obliged to give a refund if the tour is cancelled.
You will be liable to pay tax if you work. [formalllegalistic]
The bank robbers forced him at gunpoint to open the safe.
We had no choicelalternative but to sell our house; we owed the bank £100,000.
The death sentence is mandatory for drug-smuggling in some countries. [automatic;
there is no alternative]
Was sport compulsory/obligatory at your school? No, it was optional at mine.
[optional: you can choose]
I am exempt from tax as I'm a student. [free from obligation]
The negative of must and have (got) to are formed with need and have to, when we mean
something is not necessarylnot obligatory.
You don't need to/don't have to/needn't wash up; we've got a dishwasher.

Need

The grass needs cutting (badly). This plant is in need of water.
[or 'wants cutting' - informal] [more formal than 'needslwants']
The miners died through a lack of oxygen. [there was none]
There is a shortage of doctors. [there are not enough]
There's a need for more discussion on the matter. [we feel a need]

Scale of probability: 'cannot happen' to 'has to happen'
impossible -. unlikely -+ possible -, probable -+ certain -+ inevitable
Note: I've been given an opportunity to go to Bonn. [a real chance] but, Is there any
chance/possibility you'll be free next week? [chance is less formal than possibility]

120 English Vocabulary in Use