Jawaban:

Positive Sentence:

-A giraffe has a long neck.

-An elephant has a long trunk and two tusks.

-A duck has a beak and two legs.

Comparative Sentence:

-The neck of a giraffe is longer than elephants and ducks.

-The size of an elephant is bigger than giraffes and ducks.

-The body of a duck is smaller than giraffes and elephants.

Superlative Sentence:

-Giraffes have the longest neck in the animal kingdom.

-Elephants are the biggest land animal.

-Ducks are the most adorable animal.

Penjelasan:

Positive Sentence:

Basically, Positive Sentence is a sentence of that the object has, do, etc as oppose to Negative Sentence. Negative sentence main characteristic is the usage of not signifying that the subject doesn't have, don't, etc; for example, giraffe does not have a long trunk.

Comparative Sentence:

Comparative sentence is a sentence that compares the adjective of two nouns. The formula is noun 1 + to be + adj-er + than + noun 2. There are adjectives that don't have the suffix -er such as expensive; therefore, we  use more to become ... more expensive than ...

Superlative Sentence:

Superlative Sentence is a sentence that has the highest degree of the mentioned adjective such as highest, smallest, cheapest, etc. There are adjectives that don't have the suffix -est such as expensive; therefore, we use most to become ... most expensive.