▲《剑桥高级英语词典》对这两个词的解释是这样的：

1. beast: an animal, especially a large or wild one （尤指大型或野生的）动物；野兽

2. quadruped: any animal that has four legs（四足动物）

▲相关例句：

1. beast: an animal, especially a large or wild one （尤指大型或野生的）动物；野兽

Savage beasts once roamed these forests. 曾有猛兽在这些森林里出没。

He was ripped apart by savage beasts in the forest. 他在森林里被凶猛的野兽撕碎了。

The illustrations show monstrous beasts with bodies like bears and heads like tigers. 这些插图展示了怪异的野兽，它们身体像熊，头部像虎。

2. quadruped: any animal that has four legs（四足动物）

Horses, lions and dogs are quadrupeds, but humans are bipeds. 马、狮子和狗都是四足动物，但人是两足动物。

▲beast 有时也引申指“粗暴（或卑劣、凶残）的人”。如：

He was a beast to her throughout their marriage. 结婚后，他一直对她很粗暴。

Local people live in fear of this unknown sex beast. 当地人生活在恐惧中，害怕这个身分不明的色狼。