介词易错题
—When did you have the sports meeting?
—It was held ________ the morning of April 12th, and it started ________ 8:30 a.m.
A. in; on
B. on; at
C. in; at
D. on; in
答案：B
解析
本题考查时间介词 in / on / at 的区分。
1. at 用于具体的时刻点，几点几分前面一律用at，第二空后8:30 a.m.是具体时刻，所以用at。
2. on 用于具体某一天的早、中、晚，题干中 the morning of April 12th 是4月12日的上午，属于特指某一天的早上，必须用on。
3. in 用于泛指的上午、下午、晚上（in the morning）；还用于月份、季节、年份前面。很多同学看到morning直接选in，忽略后面带的具体日期，这是本题最大陷阱。
口诀：时刻用at，某天用on，泛指年月早中晚用in。
举一反三
❌ in the morning of Monday
✅ on the morning of Monday
介词固定搭配易错题
The girl is looking forward ________ a trip with her parents, but her parents are busy ________ their work.
A. to have; with
B. to having; with
C. have; for
D. having; for
答案：B
解析
本题考查两个介词固定短语，极易误选A。
1.look forward to 意为“期待”，这里的to是介词，不是不定式符号to，介词后面要接名词、代词或者动名词doing，所以是 look forward to doing，即to having。很多学生思维定势，看见to就加动词原形have，这是最常见错误。
2.be busy with sth 固定搭配，表示“忙于某事”，后接名词；be busy doing sth 表示忙于做某事。本空后面是名词their work，因此用with。
3.for不匹配这两个短语，C、D直接排除；A错在to后面用了动词原形have。
重点积累：to作介词的常考短语
pay attention to doing 注意；be used to doing 习惯于；look forward to doing 期待
变式小提醒
look forward to doing ✔
look forward to do ❌
