名词性从句是指在主句中充当名词成分的从句，它可以担任主语、宾语、表语、同位语等不同的语法功能。根据其在句中的不同作用，名词性从句可以分为以下几类：
主语从句：作为主句的主语，通常由连接词 “that” 或连接代词 “what,” “who,” “which,” “whoever,” 等引导。
- That she is an excellent pianist surprises everyone. (她是一位出色的钢琴家让大家感到惊讶。)
- What he said is completely true. (他说的完全是真的。)
- Whoever wins the race will receive a trophy. (无论谁赢得比赛都会获得奖杯。)
- Where you go after graduation is entirely up to you. (毕业后你去哪里完全取决于你自己。)
- Why she left the party early remains a mystery. (她为什么早早离开派对仍然是个谜。)
- Whether he can attend the meeting depends on his schedule. (他能否参加会议取决于他的日程安排。)
- That they are siblings surprises many people. (他们是兄弟姐妹让很多人感到惊讶。)
- What you eat affects your health significantly. (你吃什么会显著影响你的健康。)
- Whoever arrives first should start the presentation. (谁先到达就应该开始演示。)
- Where we live determines our lifestyle and habits. (我们居住的地方决定了我们的生活方式和习惯。)
宾语从句：作为主句的宾语，通常由连接词 “that,” “whether,” 或连接代词 “what,” “who,” “whom,” 等引导。
- She believes that he will arrive on time. (她相信他会准时到达。)
- I wonder if they have finished their homework. (我想知道他们是否已经完成了作业。)
- He asked me what my favorite book is. (他问我最喜欢的书是什么。)
- She told him that she loves him. (她告诉他她爱他。)
- They are discussing whether to go on a trip this weekend. (他们正在讨论这个周末是否去旅行。)
- I don’t know where she lives now. (我不知道她现在住在哪里。)
- He wonders why she is always late for class. (他想知道她为什么总是上课迟到。)
- She asked me who my best friend is. (她问我谁是我最好的朋友。)
- I doubt whether he can solve the puzzle. (我怀疑他能否解开这个谜题。)
- They are curious about what the weather will be like tomorrow. (他们很好奇明天的天气会怎样。)
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表语从句：作为主句的表语，通常由连接词 “that”，连接代词 “what”, “who”, “whose”或连接副词 “when”, “where”, “why”, “how”等引导。
- The question is whether we can get in touch with her. (问题是我们是否能与她取得联系。)
- My dream is that I can travel around the world. 我的梦想是能够环游世界。
- The ideal strategy is whatever works best. 效果最好的就是理想的战略。
- Her biggest fear is that she’ll be alone forever. (她最大的恐惧是她会永远孤独。)
- The truth is that he never really loved her. (事实是他从未真正爱过她。)
- The question is who should be responsible for the accident. 问题是谁应对这次事故负责。
- My question is whose idea works the best. 我的问题是谁的主意最有效。
- Sunday is when I relax. 星期日是我休息的日子。
- New York is where the action is. 纽约是个热闹活跃的地方。
- This is why I’ve travelled thousands of miles.这就是我走了几千英里路的原因。
同位语从句：用来解释或补充名词的意义，通常由连接词 “that” 引导。
- The fact that she failed surprised everyone. (她不及格的事实让大家感到惊讶。)
- His belief that hard work pays off is commendable. (他认为努力会有回报，这值得赞扬。)
- The idea that we should travel more resonates with me. (我们应该多旅行的想法让我感同身受。)
- The hope that peace will prevail keeps us going. (和平会战胜的希望支持着我们。)
- The rumor that they are dating spread quickly. (他们在约会的谣言迅速传开。)
- The notion that money can’t buy happiness is widely accepted. (金钱买不到幸福的观念被广泛接受。)
- The understanding that life is unpredictable motivates me to seize the moment. (生活难以预测的理解激励我把握当下。)
- The belief that education is the key to success drives her ambition. (教育是成功关键的信念推动着她的抱负。)
- The realization that time flies hits me every birthday. (时间飞逝的认识每次生日都让我感到。)
- The knowledge that honesty is the best policy guides his actions. (诚实为上策的知识指导着他的行动。)