В животе Упражнение 177. Раскройте скобки, употребляя глаголы в Present Continuous или в Present Simple.1. I (to sit) in the waiting room at the doctor's now. 2. I (not to work) in my office now. 3. Eric (to talk) about his holiday plans, but Kenny (not to listen) to him. He (to think) about his new car at the moment. 4. My friend (to live) in St. Petersburg. 5. My cousin (not to live) in Moscow. 6. The children (not to sleep) now. 7. The children (to play) in the yard every day. 8. They (not to go) to the stadium on Monday. 9. She (to read) in the evening. 10. She (not to read) in the morning. 11. She (not to read) now. 12. I (to write) a composition now. 13. I (not to drink) milk now. 14. I (to go) for a walk after dinner. 15. I (not to go) to the theatre every Sunday. 16. He (not to read) now. 17. He (to play) now. 18. He (to play) now? 19. My mother (to work) at a factory. 20. My aunt (not to work) at a shop. 21. You (to work) at an office? 22. Your father (to work) at this factory? 23. You (to play) chess now? 24. Look at the sky: the clouds (to move) slowly, the sun (to appear) from behind the clouds, it (to get) warmer. 25. How is your brother? — He is not well yet, but his health (to improve) day after day. 26. Listen! Who (to play) the piano in the next room? 27. Henry usually (to wear) glasses and now he (to wear) sunglasses. 28. Who (to listen) to music on his personal stereo over there right now?
Решение:
1)
Дано: | Решение:
V₀=54км/ч=15м/с | V(t)=V₀-at
а=0,5 м/с² | V₀-at=0
Найти: t---? | t=V₀/a=15/0,5=30(с)
ответ:вагон остановится через 30с.
2)
Дано: | Решение:
Vк=72км/ч=20м/с | Vк =V₀*at
V₀=18км/ч=5м/с | а=(Vк-V₀)/t=(20-5)/60=0,25(м/с²)
t=1мин=60с |
Найти: а---? |
ответ: а=0,25м/с².
3)
Дано: | Решение:
Vк=72 км/ч=20м/с | S=0,5t·(Vк+V₀)
V₀=36км/ч=10м/с | t=2S/(Vк+V₀)=2*1000/(20+10)=200/3(c)
S=1км=1000м | а=(Vк - V₀)/t=3*(20-10)/200=0,15(м/с²)
Найти: а---? |
ответ: а=0,15м/с².