Espero te sirva, justamente yo también estaba resolviendo este ejercicio >v<
Answer:
1) Bigger
2) Smaller
3) Taller
4) Cat is shorter than the girrafe.
5) Heavier
6)The lizard is lighter than the elephant
7) Faster
8) The turtle is slower than the rabbit.
9) Bigger
10) The mouse is smaller than the bear.
11) Heavier
12) The snake is lighter than the lion.
14) Taller
15) The boy is shorter than the grandfather.
Estoy hablando
Hope it helps