一、宾语从句的定义
在复合句中，由一个句子充当宾语，通常放在主句谓语动词（及物动词）或介词之后，这个句子就叫宾语从句。
宾语从句的引导词分为三类：从属连词、连接代词、连接副词。
例句：I finally decided that choosing an ice cream flavor is the hardest decision of my day.
二、宾语从句的引导词
（一）从属连词：that, whether, if
1. that 引导的宾语从句
that 引导的从句，表示陈述一件事实，主句谓语动词表示确定，非疑问；that 在句中无任何意义，不充当句子成分，常省略。
例句：
·I hear (that)he will be back in an hour.
·He said (that) he missed us very much.
·The teacher told us (that) the earth moves around the sun.
2. whether/if 引导的宾语从句
if/whether 意为 “是否”，说明对陈述的事物不明确或不清楚。常用在 ask, wonder, can (could) you tell me 等表示疑问、不确定意义的词之后；从句句意完整，不缺成分。
例句：
·Ask him whether (/if) he can come.
·I wonder whether it is going to rain or not.
·Could you tell me whether (/if) Mr Li lives here?
·I want to know if/ (whether) he will go to the park with us.
3. 只能用 whether 不能用 if 的情况
1.在引导主语从句、表语从句时。
例句：Whether it is true remains a question. / The question is whether it is true.
2.用在动词不定式之前时用 whether 不用 if。
例句：I don’t know whether to go there at once.
3.当与 or not 直接连用时（or not 紧跟在引导词后面时），或包含 or 引导的并列选项时，只能用 whether。
例句：I want to know whether or not you agree. / The key question is whether he is telling the truth or lying.
4. 只能用 if 不能用 whether 的情况
1.引导条件状语从句，表 “如果” 时。
例句：If he runs fast, he’ll get there on time. / I’ll go to see you if I have time.
2.在日常口语中，当主句（如 I wonder..., Do you know... ）被上下文隐含或省略，只保留核心的 “是否” 疑问从句时，通常只能用 if。
例句：If he’s coming?（= I wonder if he’s coming.）
（二）连接代词：who, whom, whose, which, what
连接代词一般表疑问，引导宾语从句，并在从句中担任句子成分，具有一定的意义，不可省略。
例句：
·He asked who could answer the question.
·Do you know whom they are waiting for?
·He asked whose bike was the best in the class.
·I don’t know whom you should depend on.
（三）连接副词：where, how, why, when
连接副词引导宾语从句，并在从句中担任句子成分，具有一定的意义，不可省略。
例句：
·He didn’t tell me when we would meet again.
·Please tell me where he is.
·Can you tell me how I can get to the station?
·Could you tell me why the train is late?
三、宾语从句的语序
宾语从句的语序必须用陈述语序，核心结构为：连接词 + 主语 + 谓语 + 其他成分
例句：
·His brother asks when he will go to the library. 他哥哥问他什么时候去图书馆。
·I don’t know what he wanted to buy. 我不知道他想买什么。
四、否定前移
若主句谓语动词为 think, guess, imagine, suppose, believe 等，其后的宾语从句若含有否定意义，一般要把否定词转移到主句谓语上，从句谓语用肯定式。
·错误：I think it is not good for your eyes.
·正确：I don’t think it is good for your eyes.
五、宾语从句的时态规则
1.主句用现在时或将来时，从句可用任何时态，根据实际情况而定。
例句：
oI don’t know how my father goes to work. 我不知道我父亲怎样去上班。
oI know he lived here ten years ago. 我知道他十年前住在这儿。
2.主句如果用一般过去时，从句的时态一般要用相应的过去时态。
例句：
oLinda said that she was going to work in Beijing in the future. 琳达说，她将来要去北京工作。
oI saw she was talking with her mother. 我看见她在和她妈妈说话。
oHe said that he had seen the movie. 他说他已经看过这部电影。
3.当从句说明的是客观真理或规律时，无论主句什么时态，从句均用一般现在时。
例句：
oHe told me the earth moves around the sun. 他告诉我地球绕着太阳转。
oMr. Li told me the sun rises in the east. 李先生告诉我太阳从东方升起。
oHe told me that there are twelve months in a year. 他告诉我，一年有十二个月。
六、练习题 + 答案 + 详解
（一）单项选择题
1.Could you tell me how long __________ ?
A. you have buy the watch
B. you have kept this science book
C. have you been away from China
答案：B
详解：句意：你能告诉我你借这本科学书多久了吗？宾语从句必须用陈述语序，排除 C 选项；how long 需与延续性动词连用，buy 是瞬间动词，不能与 how long 连用，keep 是延续性动词，故选 B。
2.The teacher asks us ____ Jim can come back on time tomorrow .
A. that B. if C. when
答案：B
详解：句意：老师问我们吉姆明天能不能按时回来。从句句意完整，不缺时间状语，排除 C；主句谓语 asks 表疑问、不确定，that 引导陈述事实的从句，if 表 “是否”，符合语境，故选 B。
3.No one knows what ______ in fifty years.
A. will our city be like
B. our city will be like
C. is our city like
D. our city is like
答案：B
详解：句意：没有人知道五十年后我们的城市会是什么样子。宾语从句用陈述语序，排除 A、C；in fifty years 表将来，从句用一般将来时，故选 B。
4.We all believe ______ China will successfully hold the 2025 Asian Games.
A. what B. that C. if D. how
答案：B
详解：句意：我们都相信中国会成功举办 2025 年亚运会。从句是陈述事实，句意完整，不缺成分，用 that 引导，that 可省略，故选 B。
5.I called Mike an hour ago, but nobody answered. I wondered ______.
A. where he is
B. where he was
C. where he has been
D. where he will be
答案：B
详解：句意：我一小时前给迈克打电话，但是没人接。我想知道他当时在哪里。主句 wondered 是一般过去时，从句需用相应的过去时态，只有 B 选项是一般过去时，故选 B。
6.In the science class yesterday, our teacher told us that light ______ faster than sound.
A. traveled B. travels C. had traveled D. would travel
答案：B
详解：句意：在昨天的科学课上，老师告诉我们光比声音传播得快。从句 “光比声音传播得快” 是客观真理，无论主句用什么时态，从句都用一般现在时，故选 B。
（二）完成句子
1.I wonder _________（whether/if）he will come to the party or not.
2.She said that she ____________ (visit) her aunt in Shanghai the next month.
答案：
1.whether
详解：从句中出现了与引导词直接连用的 or not，只能用 whether，不能用 if。
2.would visit
详解：主句 said 是一般过去时，从句需用相应的过去时态；the next month 表将来，因此用过去将来时 would visit。
（三）句型转换
1.I think he can finish the task in two hours.（改为否定句）
答案：I don’t think he can finish the task in two hours.
详解：主句谓语动词是 think，宾语从句的否定意义需要进行否定前移，把否定词加在主句谓语上，从句用肯定形式。
（四）句子合并题
1.He is doing his homework. He said.
答案：He said that he was doing his homework.
详解：主句 He said 是一般过去时，从句需用相应的过去时态，原句现在进行时要变为过去进行时；从句是陈述事实，用 that 引导。
2.How can I get to the station? Could you tell me?
答案：Could you tell me how I can get to the station?
详解：合并后为宾语从句，引导词用连接副词 how，从句必须改为陈述语序。
