3. Fill in the gaps with an appropriate modal verb (must, may, can, need, to have to).

Решение:

1. Sandra may not come to me tomorrow – I've done the job. (Выражение предположения/возможности).
2. There is no need to rewrite the essay completely – it's quite good. You only need to rewrite the third passage. (Выражение необходимости/отсутствия необходимости).
3. It's so late, we must be going! (Выражение настоятельной необходимости/обязательства).
4. Students have to pay for their education at private school. (Выражение внешнего обязательства/правила).
5. You can stay at home today. (Выражение разрешения/возможности).

Ответ: may not; only need to; must be; have to; can.