一般现在时：疑问句和否定句

在一般现在时的肯定句中，主语是 he/she/it 时动词会变化：通常加上 -s 或 -es 这样的词尾（she works、he goes）。如果需要先复习这部分，可参考 一般现在时。但一变成疑问句或否定句，主动词就要回到原形，语法变化则由 do 或 does 来体现。

对于普通实义动词，规则非常一致：疑问句用 do/does + 动词原形，否定句用 don't/doesn't + 动词原形。这个阶段最重要的例外是动词 be，留到最后再讲。（像 can 这样的特殊动词也有自己的规则，我们会另行学习。）

小窍门：只要看到 do/does 或 don't/doesn't，后面紧跟的动词就用原形——does she work、doesn't work。记住这一点就能避免最常见的错误，比如 does works 或 doesn't works。

否定句：don't/doesn't + 动词原形

要把一般现在时的句子变成否定句，在动词原形前面加上 do not 或 does not——通常缩写为 don't 或 doesn't：

• I work from home. → I don't work from home.
• They like coffee. → They don't like coffee.
• She works in London. → She doesn't work in London.
• He likes football. → He doesn't like football.

中文的否定句只需在动词前加“不”：她不在伦敦工作。英语不能直接在动词前加 not，必须用 doesn't，而且主动词要回到原形：✅ She doesn't work，绝不会是 ❌ She not works。

关键点：一旦出现 doesn't，主动词就回到原形。he/she/it 的意思已经由 doesn't 表示了——-s 不需要重复出现。所以是 ✅ doesn't work，绝不会是 ❌ doesn't works。

一般疑问句：do/does + 主语 + 动词原形

构成一般疑问句时，先用 do 或 does，然后是主语，然后是动词原形：

Do/Does + 主语 + 动词原形 … ?

• Do you work from home?
• Do they like coffee?
• Does she work in London?
• Does he like football?

同样，主动词保持原形，因为 do/does 已经承担了语法变化。所以是 ✅ Does she work?，绝不会是 ❌ Does she works?

简短回答

回答时通常不重复整个动词，而是用 do/does 或 don't/doesn't 来回答：

• Do you like tea? — Yes, I do. / No, I don't.
• Does he work here? — Yes, he does. / No, he doesn't.

注意主动词（like、work）在简短回答中不重复出现——用 do/does 或 don't/doesn't 代替它。

特殊疑问句

在 what、where、when、why、who、which、how 这类问句中，先放疑问词，然后是同样的 do/does + 主语 + 动词原形 结构：

疑问词 + do/does + 主语 + 动词原形 … ?

• Where do you work?
• What does she do?
• When do they arrive?
• Why does he leave so early?

一种特殊情况——询问主语本身。 当 who 或 what 本身就是问句的主语——也就是被问及的那个人或那件事——通常不用 do/does。动词保持一般现在时的正常形式，如果答案是 he/she/it，就要加 -s：

• Who works here?（正常、中性的问法，不说 Who does work here?）
• What happens next?（不说 What does happen next?）

把两种结构放在一起对比：

• Who do you see every day? = 你看见某人 → 用 do。
• Who sees you every day? = 某人看见你 → 正常问法不用 do，动词加 -s。

例外：动词 be

在普通动词中，be 是唯一不用 do/does 的。它自己构成否定句和疑问句，因为 am/is/are 本身就相当于助动词——不需要 do/does。

• 否定句：I'm not tired. · She isn't happy.（不说 doesn't be）
• 疑问句：Is she happy? · Are you ready?（不说 Does she be…?）

因为这个动词非常常用，用法又不一样，它有自己单独的一课——见 动词 "to be"。

常见错误

• ❌ She doesn't works. → ✅ She doesn't work.（doesn't 后面用动词原形）
• ❌ He don't like it. → ✅ He doesn't like it.（he/she/it 要用 doesn't，不是 don't）
• ❌ Does she works here? → ✅ Does she work here?（does 后面用动词原形）
• ❌ Where you work? → ✅ Where do you work?（疑问句需要 do/does）
• ❌ Does she be happy? → ✅ Is she happy?（be 不用 do/does）

快速检查

把句子变成否定句，或者写出疑问句：

1. （否定句）He likes tea. → He ____ tea.
2. （疑问句）They work on Saturdays. → ____ they ____ on Saturdays?
3. （特殊疑问句）She goes there by bus. → How ____ she ____ there?
4. （否定句）I am ready. → ____ ready.

要点回顾

• 一般现在时的否定句用 don't（配 I/you/we/they）或 doesn't（配 he/she/it）+ 动词原形。
• 一般现在时的疑问句用 do 或 does + 主语 + 动词原形。
• 在 do/does/don't/doesn't 后面，主动词失去 -s：doesn't work（不是 works），Does she work?（不是 works）。
• 用 do/does 或 don't/doesn't 简短回答；特殊疑问句的结构是疑问词 + do/does + 主语 + 动词原形。
• 当 who/what 是主语时，不用 do/does，保持一般现在时的正常形式：Who works here?
• 动词 be 是例外——am/is/are 自己构成否定句和疑问句：isn't、Are you…?