1） 用half of, part of, most of, a portion of 等词引起主语时，动词通常与of后面的名词，代词保持一致。
Most of his money is spent on books.
Most of the students are taking an active part in sports.
2） 在一些短语，如 many a 或 more than one 所修饰的词作主语时，谓语动词多用单数形式。但由more than… of 作主语时，动词应与其后的名词或代词保持一致。
Many a person has read the novel. 许多人都读过这本书。
More than 60 percent of the students are from the city.百分之六十多的学生都来自这个城市。