什么是介词（Prepositions）？
介词是用于表示名词（或代词）与其他词之间关系的词，通常说明时间、地点、方向、方式等。 虽然介词本身很短，但它们在句子中起着至关重要的作用。
例如：
• She is in the room.
• The book is on the table.
• We’ll meet at 5 p.m.
• She is in the room.
• The book is on the table.
• We’ll meet at 5 p.m.
常见英语介词分类
- 时间介词：at, on, in, by, during, since, for
- 地点介词：at, on, in, under, over, between, beside
- 方向介词：to, into, onto, toward, through
- 方式/原因介词：by, with, because of, due to
经典用法对比
in / on / at 表时间：
in用于较长时段：in July, in 2025, in the morningon用于具体日期或某天：on Monday, on Christmas Dayat用于具体时刻：at 6 a.m., at noon, at night
in / on / at 表地点：
in表示“在……内部”：in the box, in Chinaon表示“在……表面”：on the wall, on the deskat表示“在……点/位置”：at the door, at the station
小测验：选对介词！
请选择正确的介词完成句子：
“The cat is sleeping ___ the sofa.”