cat n. 猫
1.The cat is playing.
那只猫在玩耍。
cow n. 母牛，奶牛
1.We milk the cow.
我们挤牛奶。
dog n. 狗
1.Some people keep dogs in their houses.
有些人家里养狗。
duck n. 鸭子
1.How many ducks are there in the river?
河里有多少只小鸭？
pig n. 猪
1.He keeps pigs as a career.
他以养猪为业。