Ответьте на вопросы к тексту

1. What is the building held by?

2. What is the structure of the glazed cylinder?

3. What do the portal frames consist of?

4. What are the features of the two middle portal frames?

5. Why do the longitudinal beams have to span large distances?

6. What are the features of the ground floor portals?

7. What elements of the structure required welding?