2016公共英语等级考试二级语法词汇辨析：介词
容易混淆的介词：
表时间的介词 at, on, in at表示“在几点几分”(单位最小);on表示“在具体的某一天或某天上午(下午晚上等)”;
in表示“在几天、周、月、年”。 I get up at six o’clock.
It happened on a spring morning.
There are seven days in a week.
in the morning / evening / afternoon;at noon / night / dawn / sunrise / sunset / lunch / dinner / supper, etc.
during, for, in for后加一个“表时间段的具体单位(常用复数)”;during强调“持续”或“某活动”期间;in指在一段时间内。 She has lived here for six years.
He was in English during the war.
In those days he was poor.
till, until till/until构成的短语修饰“持续性动词”，“非持续性动词”要用“否定式”。 They waited till/until 10:00.
They didn’t leave until/till 10:00.
after, since “after+时刻或时段”，“…以后”，终点时间在过去或将来;而“since+时间点”，“自从…以来”，终点在说话的时刻。 She’ll be back after eight o’clock.
She’s lived here since 2002.
in, after “in+时段”，“…以后”，用于将来时;“after+时刻或时段”，“…以后”可用于将来时或过去时。 He’ll leave after 11:00.
He left after 11:00.
She left after a few hours.
She’ll be back in half an hour.
