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7. The fridge is full, so we needn't go shopping.

8. We've got a dishwasher, so you needn't wash-up.

9. What time do we have to be at the railway station?

Exercise  5

1) You mustn't smoke here. - a) not allowed

2) Jim can climb a mountain very fast. - c) when you are able to do something.

3) This work must be done at once. - b) you are obliged to so something.

4) He must consult his teacher. - d) there is a necessity in doing something.