Match the sentences with the functions of the modal verb "to be to".

Write one number (1–4) in each gap.

People are to explore the Universe. It's in our nature to discover new things. [ ]

The uniform is to be clean and neat. [ ]

Mrs Black is not to talk to the prisoners. [ ]

Diamonds are not to be mined without special equipment. [ ]

1. Impossibility of an action or event.

2. A prohibition.

3. An inevitable event.

4. An order.