1 What lovely weather!
-> How lovely the weather is!
2 The boy is so intelligent!
-> What an intelligent boy!
3 Keangnam is the tallest building in Hanoi.
-> No building in Ha Noi is taller than Keangnam.
4 She is the most fascinating woman I have ever met.
-> I have never met such a fascinating woman before.
5 She has never seen such a big flower!
-> This is the first time she has ever seen such a big flower!