6)“a portion of , a series of, a kind of, a body of, a species of, a pair of+名词”作主语时,其谓语动词一般用单数形式。
【例如】
A series of accidents has occurred recently in America.
A pair of new glasses is quite expensive.
7)事件、机构、国名、作品等专有名词作主语时,谓语动词用单数。
【例如】The Adventures of Huckleberry Finn was written by Mark Twain and it is an interesting book.The United Nations is an organization to defend world peace.