Сначала находим глагол-сказуемое (выделены подчеркиванием) и определяем по нему время, потом образуем "хвостик":
1. In New York, most people<u> go </u>to work by subway, don't they?
2. The service life of steel sleepers<u> is </u>from 35 to 60 years, isn't it?
3. About 60 % of the world's railroad network <u>has been built </u>to standard gauge (1,435 mm), hasn't it?
4. Transport <u>plays</u> a very important part in the development of economy, doesn't it?
5. At Richmond, a lot of passengers <u>got</u> off the train, didn't they?
6. Each one of your suitcases <u>will be checked</u> when you go through the customs, won't it?
7. Susan <u>has bought</u> a newspaper and a magazine to read on the train, hasn't she?
8. Competition between different modes of transport <u>is intensifying</u> now, isn't it?
9. The Disneyland train called “The Excursion” <u>was built </u>specially for carrying visitors through the Grand Canyon Diorama, wasn't it?
10. When inactive, locomotives are housed in a train depot, aren't they?
11. Perishable (скоропортящиеся) goods <u>should be carried</u> in refrigerator cars, shouldn't they?
12. The automatic train control<u> facilitates</u> (облегчает) the work of a locomotive driver, doesn't it?
13. Long-welded rails (бесстыковые рельсы) <u>have been used</u> on main railways since 1960s, haven't they?
14. The US <u>ranks</u> first in the world in the volume of freight traffic, doesn't it?
15. The construction of the railway bridge <u>had been completed</u> by the beginning of the navigation season, hadn't it?
