这三句都表示赞同，但程度不同。I completely agree 表示你完全赞同，对方说的每一点都赞同——语气最强，而且中性，什么场合都能用。You've got a point 亲切、随意；表示你赞同他说的某一点，不是全部。I see what you mean 温和、中性；表示你理解他的想法并且部分赞同，后面常常接一个小小的 'but'。
表示赞同
I completely agree — I completely agree. Trains are better.
You've got a point — You've got a point about the price.
I see what you mean — I see what you mean.
Not "I completely agree, but the price is too high." — say "You've got a point, but the price is too high.". 只有全部同意时才用 I completely agree。如果你只同意其中一部分、还想接一个 'but'，就说 You've got a point。
试一试: Amina: We should travel by train. It's better for the environment. Hiroshi: ___ It's much greener. Hiroshi agrees fully with Amina. Which fits? (I completely agree. / I'm afraid I disagree. / I'm not sure about that.) 答案: I completely agree. — I completely agree 表示完全赞同，正合适。I'm afraid I disagree 和 I'm not sure about that 都带有怀疑或不赞同的意思，都不是在表示赞同。
礼貌地表示不赞同
这三句都表示不赞同，但都很客气——从委婉到最委婉。I'm afraid I disagree 明确表示你不赞同；“I'm afraid” 只是让语气礼貌，所以正式场合也能用。I don't really agree 是同样的意思，语气更软、更随意。I'm not sure about that 最委婉：表示你对这个想法有疑问，而不是直接说“不”。
I'm afraid I disagree — I'm afraid I disagree about the time.
I don't really agree — I don't really agree with that.
I'm not sure about that — I'm not sure about that.
Not "No, you're wrong." — say "I'm afraid I disagree.". 英语里表达不同意要委婉。直接说 'you're wrong' 会显得没礼貌——I'm afraid I disagree 用礼貌的方式表达了同样的意思。
试一试: Sofia: The train is faster than the car. Diego: ___ I think the car is quicker. Diego politely disagrees. Which fits? (I'm not sure about that. / I completely agree. / You've got a point.) 答案: I'm not sure about that. — I'm not sure about that 礼貌地表达了怀疑，正好对应 Diego 的不赞同。I completely agree 和 You've got a point 都是在表示赞同，都不是在表达不赞同。
试一试: Amina: The film was good, but it was far too long. Hiroshi: ___ It really needed to be shorter. Hiroshi agrees with only one part — that it was too long. Which fits? (You've got a point. / I completely agree. / I'm afraid I disagree.) 答案: You've got a point. — You've got a point 只同意其中一部分——这里指电影太长了——正好对应 Amina 的话只说对了一半的情况。I completely agree 意思是你全都同意，包括电影很好看这一点；I'm afraid I disagree 又是完全不同意。所以这两个都不适合只同意一部分的情况。
强烈、温和，和太直接
这些回答的差别在于语气有多强。强烈同意：Absolutely!、I couldn't agree more、That's so true! 温和同意：You're right、I suppose so（同意，但不太起劲）。礼貌反对：I see it differently、I don't think so、I have to disagree。No way!、That's not true 和 You're wrong 留给朋友——对陌生人或上司说太直接了。
Absolutely! — Absolutely! I love the warm weather too.
I couldn't agree more — I couldn't agree more! Everyone should learn a language.
You're right — You're right. Regular exercise helps a lot.
I suppose so — I suppose so, but I am not sure.
I see it differently — I see it differently — movies can be better.
No way! — No way! I completely disagree.
试一试: Yasmin agrees very strongly with Liam about summer. Which fits? (Absolutely! / I suppose so / I see it differently) 答案: Absolutely! — Absolutely! 是强烈同意，正合“非常同意”的意思。I suppose so 只是勉强同意，I see it differently 是不同意，所以两个都不算强烈同意。
试一试: Ira disagrees with her manager and wants to stay polite. Which fits? (I see it differently / You're wrong / No way!) 答案: I see it differently — I see it differently 是礼貌地表示不同意，这正是 Ira 跟上司说话时需要的。You're wrong 和 No way! 在职场里太直接了——留给亲近的朋友吧。