Kate has left home for school.可作副词也可作名词，意思是“在家”
house指“住宅”、“住房”The Greens live in a big house.

2.man总称“人”、“人类”，用单数
people泛指“人们”，表示复数概念:People often work in the day.
指“人”的个体，但只表示复数概念:There are five people in my family.
前面加定冠词指“人民”，表示复数概念:Let’s work for the people.
指“民族”时，有单、复数之分:The Chinese people is a hardworking people.
person强调“人”的个体，有单、复数之分:There are five persons in my family.

3.police总称“警察”，表示复数概念:
policeman强调“警察”的个体，有单、复数之分:My father is a policeman.

4.universe指“宇宙万物”，强调物质概念:
When we talk about the universe，we mean the earth， the sun，the moon and many other stars.
space指“太空”、“宇宙空间”，强调空间概念:
Many countries have sent up the satellites into space.
“空间”、“余地”、“空地”:There is no space on the bus.

5.不同国家的人的单复数:

名称	总称(谓语用复数）	一个人	两个人
中国人	the Chinese	a Chinese	two Chinese
瑞士人	the Swiss	a Swiss	two Swiss
澳大利亚人	the　Australians	an　Australian	two　Australians
俄国人	the Russians	a Russian	two Russians
意大利人	the Italians	an Italian	two Italians
希腊人	the Greek	a Greek	two Greeks
法国人	the French	a Frenchman	two Frenchmen
印度人	the Indians	an Indian	two Indians
加拿大人	the Canadians	a Canadian	two Canadians
德国人	the Germans	a German	two Germans
英国人	the English	an Englishman	two Englishmen
瑞典人	the Swedish	a Swede	two Swedes
日本人	the Japanese	a Japanese	two Japanese
美国人	the Americans	a American	two Americans