Fill in the gaps with suitable prepositions or adverbs where necessary:
1. The plant's operators decided to shut____the reactor.
2. Differences___ people's earnings depend____ a wide variety____ factors.
3. This trend will raise a number_____ issues relating___ the economic concerns____ the country.
4. Huge advances______ the development_______ technologies have substantially facilitated the production process.
5. The invention _____ printing______ the 15th century completely changed the world
6. The deal involved the supply_____ forty new aircrafts____ the airlines.
7. The town was turned_____ a flourishing seaside destination.