Ответ:
1) This bar of chocolate is tastier than the one I bought at supermarket yesterday.
2) This story is the most interesting in the book.
3) Elephants are bigger than lions.
4) Train tickets are cheaper than plane tickets.
5) Hoverla is the highest mountain in Ukraine.
6) Planes are the fastest means of transport.
7) That was the most tiring trip that I have ever had.
8) My little brother believes that dinosaurs were the most dangerous animals in the world.