定义

主谓宾结构核心：主语 S + 谓语 V + 宾语 O (Object)

• 名词做宾语

• 代词做宾语

• 非谓语动词（动名词，不定式）做宾语

宾语从句（object clause）在句中充当宾语，通常位于及物动词、介词或某些形容词之后。

• We talked about what we should do next.

• I am sure that you will pass the exam.

引导词

连接词 that

无意义、在从句中不做成分、有时可省略

省略规则

• 通常省略：当主句谓语是 think / say / believe 时

• 不可省略

  • 从句较长或有多个从句时

    • 补充：当动词后接多个由 that 引导的宾语从句时，第一个 that 可省，但后面的 that 不可省。

      • He said (that) you were too young and that he wouldn't tell you.

  • 当主句谓语与从句之间有插入语时。

    • I realized at that moment that I had made a mistake.

  • 当 that 作介词 except, but, besides 等的宾语时。

    • The movie is perfect except that the ending is a bit rushed.

连接代词 what / how

有意义，在从句中做主语/宾语/表语

• I know what you need. （what 做从句宾语）

• She asked who could help her （who 做从句主语）

连接代词 which / whose

有意义，在从句中做主语/定语

• I wonder whose bag it is.（whose 做从句定语）

• He doesn’t know which book is his（which 做从句定语）

• I don’t know which is better.（which 做从句主语）

连接副词 when / where / why / how

有意义，在从句中做时间/地点/原因/方式状语

• He asked when we should start.

• Please tell me where you live.

• I don’t know why he left.

• She showed me how she cooked.

从属连词 whether / if

表是否，不做成分；whether / if 有时可互换

作用：均表示“是否”，引导具有疑问含义的宾语从句

whether / if 互换

在动词后作宾语时，两者常可互换。例外（只能用 whether）：

• 位于介词之后

  • It all depends on whether they will support us.

• 与 or not 连用时（固定搭配 whether or not）

  • I'll let you know whether or not I can come.

• 引导不定式短语

  • She hasn't decided whether to go or stay.

当引导主语从句（放句首）、表语从句、同位语从句时，只能用 Whether

情景规则

语序规则

宾语从句必须使用陈述句语序（主语 + 谓语），即使原句是疑问句，变为宾语从句后也要改为陈述语序。

• 错误示范：I don't know where is he.

  正确示范：I don't know where he is.

时态呼应

主句为现在时或将来时：从句可根据实际情况使用任何时态。

• He says that he is tired. (现在)

• He says that he was tired yesterday. (过去)

• He says that he will be tired tomorrow. (将来)

主句为过去时：从句常发生时态后移（backshift），尤其在间接引语或转述类结构（indirect / reported speech）中

• 一般现在时 → 一般过去时：He said that he was tired.

• 一般将来时 → 过去将来时：He said that he would come.

• 现在完成时 → 过去完成时：He said that he had finished.

常发生 —— 意味着这不是绝对规则：如果从句内容在现在仍然真实、仍然相关，或属于客观真理 / 自然现象，通常不后移，仍可用现在时

• The teacher told us that light travels faster than sound.（客观真理）

• I just learned that there is an app called XXX.（仍然存在）

  • 如果说话人想把该信息明确放在过去，也可以用过去时

    • I just learned that there was an app called XXX.

否定转移

l  当主句主语为第一人称（I/we），谓语动词为 think, believe, suppose, expect 等表示“认为/相信”的词时，从句的否定词通常转移到主句上。

• I don't think （that）he is right. (实际含义：我认为他不对。)

• We don't suppose it will rain. (实际含义：我们不认为会下雨。)

虚拟语气

当主句动词表示“建议(suggest, advise, propose)”、“要求(demand, request, require)”、“命令(order, command)”、“坚持(insist)”时，宾语从句需用虚拟语气，即“（should）+ 动词原形”。【注意这里的 should 可以省略】

• I suggested that he (should) study harder.