Why do we sleep? from birth, we (spend) a third of our lives asleep but scientists srill (not/know) exacly why.
why (humans/have) problems sleeping? in modern society, many people (not/get) the recommended seven or eight hours a night. we (work) long hours and we rarely (go) to bed at sunset.
why (we/sleep) differently? it (depend) on the time of year and also our age. teenagers always (need) more sleep than adults. lots of elderly people (not/sleep) longer than four or five hours, but they often (take) naps during the day.
1. spend
2. don't know
3. do humans have
4. don't get
5. work
6. go
7. do we sleep
8. depends
9. need
10. don't sleep
11. take
Объяснение:
Весь текст в Present Simple