主谓一致是指：1）语法形式上要一致，即单复数形式与谓语要一致。2）意义上要一致，即主语意义上的单复数要与谓语的单复数形式一致。3）就近原则，即谓语动词的单复形式取决于最靠近它的词语，一般来说，不可数名词用动词单数，可数名词复数用动词复数。There is much water in the thermos.但当不可数名词前有表示数量的复数名词时，谓语动词用复数形式。e.g.Ten thousand tons of coal were produced last year.Large quantities of water are needed.In western countries,mountains of rubbish are thrown away each day.1并列结构作主语时谓语用复数Reading and writing are very important.注意：当主语由and连结时，如果它表示一个单一的概念，即指同一人或同一物时，谓语动词用单数，and此时连接的两个词前只有一个冠词。The iron and steel industry is very important to our life.