мне нужна главная тема в тексте ,,Снап" (Ернест Сетон Томсон надо

I would like to talk about the role that computers play in our lives. These machines appeared quite a long time ago - in the middle of the last century. Initially, computers were huge, enormous machines, but over time, their size has decreased and their quality has improved. People have invented for themselves indispensable helpers in their work, socializing with friends, and entertaining themselves. Computers help us make our shopping lists, remind us about important appointments and anniversaries, help us answer the telephone. We can`t imagine our lives without computers.
Many people have got used to such state of things and they can no longer do without  computers. So now we can see a kind of dependence on computers and computer games. Of course, this is bad, because it destroys people, ruins their health and lives. As the result they can end up going crazy because computer addiction is akin to drug addiction, very difficult to recover from.
Thus, I believe that we should be able to control their actions and not to make ourselves slaves of "iron robots" letting them ruin our future. I believe that we should not overuse the benefits provided to us by computers. Otherwise modern technology will devour us.

1."When does the train depart?" 2."One has just (departed) and the next (starts) in half an hour."
3. He ( booked) tickets,(went) to the platform and (boarded) the train.
4. The locomotive ( was running) at the highest speed when the engine-driver saw that the line was damaged.
5. Yesterday's newspaper  stated) that the traffic (would/will increase) greatly in the near future.
6. Many foreign tourists (are travelling) in our country at present.
7. The City Soviet (will have  built) a new terminus by the end of this year.
8.We knew the track (needed) reconstruction at that time.
9. When we (get) to Minsk, we (will ask) for the time-table.
10. If we do not ( find) a porter, we (will take) our things ourselves.
11. As soon as I ( find) a porter, we (shall give) him our things and start) for the platform.
12. When we (get) to Sochi,we (shall leave) our luggage at the station.
13. If there is) time before the train  leaves) for Gagry we shall go) to a restaurant and ( have) breakfast.
14. I don't know if we (shall find) a restaurant open at such an early hour.