| MUST |
| Non-negative: must Uncontracted negative: must not Contracted negative: mustn`t |
| � MUST is used to express obligation or compulsion in the present tense (= to be obliged to do something, to have to do something) |
| Eg |
| You must be back by 10 o`clock |
| � MUST also expresses prohibition, when it is in negative form |
| You mustn`t smoke here |
| � Must is used to deduce something |
| She must be in her forties |
| Eg |
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