Sure! Here's the completed text with the suitable forms of the adjectives in brackets:

London is one of the (1. large) **largest** cities in the world. Its population is a lot (2. small) **smaller** than Tokyo or Shanghai, but it is by far (3. popular) **the most popular** tourist destination. London is probably most famous for its museums, galleries, palaces, and other sights, but it also includes a (4. wide) **wider** range of peoples, cultures, and religions than many other places. People used to say that it was (5. dirty) **a dirty** city too, but it is now much (6. clean) **cleaner** than it was. To the surprise of many people, it now has some of (7. good) **the best** restaurants in Europe too. For some people, this makes London (8. exciting) **the most exciting** city in Europe.