1. The doctor said, "The child is very ill. He must be taken to the
hospital at once." 2. A man should help his parents when they become
old. 3. There are no buses or taxis, so we have to walk. 4.
Everybody should learn a foreign language. 5. We can't live without food
and water. We must eat and drink. 6. I have to get up early tomorrow,
so I must go to bed late tonight. 7. You can't drive a car at
night without lights. 8. Man can't live by bread alone. 9. The
matter is to be discussed in tomorrow's debate. 10. You shouldn't sit there
in your wet clothes; you will catch cold it you do. 11. They needn't do all
the exercises; it will be sufficient if they do four of them.