这三个说法都用来引出你的看法，但并不一样。I think = 日常、中性的选择；语气略微柔和，最适合随意的聊天。I believe = 更强、更正式；表示你很确定。In my opinion = 明确表示整个想法是你个人的看法，适合讨论或写作。一句话只用其中一个开头。要表示你和别人看法相同，用 I agree——它是动词，所以说 I agree，绝不能说 "I am agree"。
表达看法
In my opinion — In my opinion, this museum is interesting.
I think — I think it is a good plan.
I believe — I believe we should wait.
I agree — I agree with you completely.
Not "In my opinion I think this is the best plan." — say "In my opinion, this is the best plan.". 句子开头只用一个表达看法的短语。把 In my opinion 和 I think 叠在一起用，听起来是错的。
试一试: Mei: What do you think of this museum? Lars: ___ it is really interesting. Lars wants to give his opinion. Which fits best? (In my opinion, / afraid of / proud of) 答案: In my opinion, — In my opinion 引出你的想法，正合适。Afraid of 和 proud of 都是在描述感受，都不是在引出一个看法。
谈论感受
用这些说法来表达你的感受。interested in 某样东西 = 你想多了解它。afraid of 某样东西 = 它让你害怕，通常是真的有危险。proud of 某件事 = 你做得好，心里很自豪。nervous（about）某件事 = 难事临头之前的紧张。注意区别：afraid of 是怕危险的东西，nervous about 是考试这类事情之前的紧张。还有三个词说的是事物本身，不是你：exciting 的事让你兴奋，frustrating 的事让你气恼，因为你怎么也做不好，moving 的事让你感动，常常看得想哭。
interested in — I'm interested in modern art.
afraid of — I'm afraid of spiders.
proud of — I'm proud of my work.
nervous — I'm nervous about the exam.
exciting — The concert was so exciting!
frustrating — This puzzle is frustrating — I can't solve it.
moving — That story was so moving. I cried at the end.
Not "I'm afraid of my exam tomorrow." — say "I'm nervous about my exam tomorrow.". 考试并不危险，所以事情之前的担心要用 nervous about。afraid of 留给真正让你害怕的东西，比如蜘蛛或恐高。
试一试: Camila: You finished the whole project by yourself! Farid: Yes, I'm ___ my work. Farid did a good job and feels good about it. Which fits? (proud of / afraid of / nervous about) 答案: proud of — Proud of 描述的是对自己做得好的事感到满意，正合适。Afraid of 是关于害怕，nervous about 是关于担心，都不是在表达对自己成果的好感受。