Question

At the pet shop

Parrots are .......... Expensive..........iguanas
Iguanas are not ........... Expensive...........parrots.
Cats are .............. Expensive........ Dogs.
Snakes are ................... Than frogs

Answer 1

more expensive than
as expensive as
as expensive as 
more expensive 

faltam dados na sua pergunta, mas acho que é isso o que você buscava.