卫生类：基础语法回顾and
7.and 连接两个名词做主语时，谓语原则上用复数，但是两个名词若构成一个整体事物时，谓语则用单数。如：The teacher and his son are picking apples now.(老师和他的儿子在摘苹果) / Fish and chips is very famous food. (鱼和薯条是一种出名的食品)
8. there be 句型中be的单复数一般由靠近的名词决定。如：There is a table and four chairs in the room.(房间里有一张桌子和四张椅子)
9.用both…and…连接两个事物做主语时，谓语一般用复数。如：Both you and I are required to be here tomorrow.(你和我明天要求都来)
10.主语中含有with的短语时，谓语单复数由with之前的人物决定。如：A woman with a 7-year-old child was standing at the side of the road. (一名妇女带着一个七岁的孩子(当时)就站在路边)
11.either…or…或者 neither…nor…连接两个人物做句子主语时，谓语采用就近原则。如：Either you or he is right.(要么是你对，要么是他对。/你和他有一个人是对的) / Neither you nor I am going there.(你和我都不打算去那里)
12.表示一段时间或长度概念的复数名词做主语时，谓语一般用单数。如：Two months is not a short time.(两个月不是个短时间)Two thousand kilometers is quite a long distance(距离).(两千千米是相当长的一段距离)
13.主语中含有half of… / (three quarters)of… / all (of) the ….等词语时，谓语的单复数由名词确定，如：Over three quarters of the information on the Internet is in English.(因特网上四分之三以上的信息是用英语写的) / A third of the students were playing near the lake.(学生的三分之一(当时)正在湖边玩耍) / All of the water in these rivers has been polluted.(这些河流中的水已经被污染了)(被动句)
但是，population一词又有特殊情况： What’s the population of China?(中国人口是多少？)(句子用单数) / Three quarters of the population in this city are Arabs(阿拉伯人).(这个城市四分之三的人口是阿拉伯人)(句子用复数)