biped|bipeds

鸡是农场里常见的两足动物。

Chickens are common ___bipeds in the farm.

大多数鸟类是两足动物，因为它们用两条腿行走。

Most birds are ___bipeds because they walk on two legs.

袋鼠是少数用两条腿走路的哺乳动物之一。

Kangaroos are one of the few mammals that are ___bipeds.