一全文逐句语法解读
本课围绕 超速被拦，重点是 must have been / must have done（表对过去的推论）与 do you think 作插入语的用法。
¶ 1 · must have been 表对过去的推论（句 4、9）
| 句子 | 语法点 |
|---|
| You must have been driving at seventy miles an hour. | 推论 must have + 过去分词，表对过去的肯定推测 |
| I can't have been. | 否定式 can't have been，表“不可能（是那样）” |
| I must have been dreaming. | must have been + 现在分词，表当时一定正在…… |
¶ 2 · do you think 作插入语（句 3）
| 句子 | 语法点 |
|---|
| Where do you think you are? | do you think 用在特殊疑问句中作插入语，征询看法 |
| On a race track? | 承接上文的省略句，表追问 |
| I was doing eighty when I overtook you. | 过去进行时 + when 从句，表“我正在……时” |
¶ 3 · had better 与请求（句 13、15、20）
| 句子 | 语法点 |
|---|
| your driving licence | 驾驶执照。driving 作定语修饰 licence |
| you'd better not do it again | had better 的否定式：had better not + 动词原形 |
| you'd better take my advice | take one's advice = 接受某人的劝告 |
二固定搭配与重点词组
| 短语 | 用法与例句 |
|---|
| at seventy miles an hour | 以每小时七十英里的速度。 |
| the speed limit | 限速（标志）。 |
| driving licence | 驾驶执照。 |
| had better (not) do | 最好（别）做……。 |
| take one's advice | 接受某人的劝告。 |
| must have done | 一定做过……（对过去的肯定推测）。 |
三语法核心总结
- must have + 过去分词 表对过去情况的肯定推测；否定式用 can't have + 过去分词。
- do you think 可作插入语，用在特殊疑问句中征询意见：Where do you think you are?
- had better 的否定式是把 not 放在 better 之后：had better not do it again。
- 本课生词 10 个全部嵌入课文句子，无遗漏。