Fill in must, mustn't or needn't as in the example: 1. You ... drink your milk. 2. You ... do the washing-up. I'll do it. 3. You ... throw litter in the street. 4. I ... iron all these clothes.

Solution:

• 1. You must drink your milk. (It is advice or necessary for health.)
• 2. You needn't do the washing-up. I'll do it. (It is not necessary for you to do it.)
• 3. You mustn't throw litter in the street. (It is forbidden.)
• 4. I must iron all these clothes. (It is necessary to iron them.)

Answer: 1. must 2. needn't 3. mustn't 4. must