“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.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.
after, in, within(A) after表示“在……之后”，是before的反义词。如：He got a cancer and died after a year.?The meeting will end after 3:00pm. 会议将在下午三点后结束。(B) within“在……时间之内”。如：I can finish it within an hour. 我不需一小时就可把它做完。注：after与in都可表示“在……之后”，但after后可跟时间段，也可跟时间点；而in后必须跟时间段。after既可用于将来时，也可用于过去时，而in只能用于将来时。I’ll arrive in an hour. 我一小时后到达。</p 产品：澳博培训供货总量：不限产品价格：议定包装规格：不限物流说明：货运及物流交货说明：按订单
