Comparing Animals hen we compare two things we generally add "-er to the adjective and use the word "than". The giraffe is taller than the zebra. k 1. Complete the sentences comparing the animals using the "-er" form and the word "than". The mouse is (small) the horse. The cat is the dog The turtle is (clean) (slow) the rabbit. The horse is (fast) the cow. .. When an adjective has a CVC formation, we double the final consonant. (i.e. fat - fatter)