Verified answer

1. He looked forty, but I knew he must be much less than that.  

2. It must be wonderful to be able to get away just like that.  

3. You mustn’t miss the film. It’s very good.  

4. You mustn’t cross the street when the light is red.  

5. Must I go now? – No, you needn’t, if you don’t want to.  

6. Must he do everything himself?  

7. Do you know what must be done?

8. When must I give it back to you?