Задайте разделительные вопросы к следующим предложениям.
1. Perishable goods should be carried in refrigerator cars, shouldn't they ?
2. The automatic train control facilitates the work of a locomotive driver, doesn't it ?
3. George Stephenson built the world's first public railways: the Stockton and Darlington railway in 1825 and the Liverpool-Manchester railway in 1830, didn't he ?
4. An impact-resistant windscreen will reduce the risk of injury to the driver in case of any accident, will not it ?
5. The construction of new railway lines is always preceded by long and thorough
surveying work, isn't it ?
6. Long-welded rails have been used on main railways since 1960s, haven't they ?