Task C. Complete the sentences with must or mustn't.

Task C. Using 'must' or 'mustn't':

• 1. You mustn't animals at the zoo. It's dangerous. (It's forbidden and dangerous to touch or feed zoo animals).
• 2. You mustn't eat in the library. (Eating is not allowed in libraries).
• 3. You must wear a uniform at school. (Wearing a uniform is usually a requirement).
• 4. You mustn't walk on the grass. (Often there are signs prohibiting walking on the grass in parks or gardens).
• 5. You must listen to your parents. (It's a general rule to listen to parents).
• 6. You mustn't drop litter in the streets. (Dropping litter is socially unacceptable and often illegal).
• 7. You mustn't use a mobile phone in the class. (Mobile phone use is typically restricted during lessons).

Explanation: 'Mustn't' is used for prohibitions or things that are forbidden, while 'must' is used for strong recommendations or obligations.

Answer: 1. mustn't, 2. mustn't, 3. must, 4. mustn't, 5. must, 6. mustn't, 7. mustn't