雅思口语和写作中常见同义词的汇总：
同义词辨析：手术
「operation」这个单词的中文释义就是「手术」，但是如果我们看其英文释义的话，会发现这个单词所指的范围会更精确一些：
-the process of cutting into someone's body to repair or remove a part that is damaged
-e.g. He had an operation to remove a blood clot from his brain.
「procedure」同指「手术」，但是主要是专业术语，一般是在医疗行业工作的人会使用，
-an operation performed in a particular way on a particular part of the body.
-e.g. The procedure normally only takes a few minutes.
「transplant」作为名词在这里就是指「器官移植了」
-an operation to remove an organ from one person's body and put it into another per-son's body
-e.g. There is a shortage of donors for heart transplants.
-e.g. She had to have a kidney transplant.
「surgery」虽然中文意思同样是「手术」但是如果我们仔细阅读其英文释义，我们会发现这个单词所指的范围比「operation」更大一些：
-medical treatment involving an operation
-e.g. She required surgery on her right knee.
-e.g. He was taken in for surgery.
「plastic surgery」指的是「整容手术」
「bypass」指的是「心脏搭桥」
同义词辨析：承诺
「promise」是我们最熟悉的表示「承诺」的单词，但是这个「承诺」并不可靠：
-a statement that you will definitely do or provide something, which may not be reliable
-e.g. Politicians are always making promises.
「pledge」相比与「promise」，这个单词指的是「公开的，正式的，官方的」，往往是来自「政府」或是「某组织」：
-a public or official promise to do a particular thing in the future
-e.g. The Government has fulfilled at least 50% of its election pledges.
-e.g. We have received pledges of help from various organizations.
「vow」这个词对应中文的「誓言」，非常严肃认真的承诺；搭配动词「take/make」：
-a very serious promise to do something or not to do something that you choose to make
-e.g. He made a vow never to drink alcohol again.
-e.g. your marriage vows
「oath」这个词同样对应「誓言」，但是使用语境和「vow」相比不一样一些，多数出现在「法庭宣誓」这个语境下；搭配动词「take/make/swear」：
-a formal promise, especially one that someone makes in a court of law:
-e.g. Witnesses swear a solemn oath to tell the truth.
-e.g. Public officials must take an oath to support the US Constitution.
「undertaking」是指一种「正式承诺」，而承诺的内容往往是一些「艰难的事情，往往需要大量的投入」，关联度比较高的同义词是「pledge」：
-a serious or public promise to do something, especially something difficult which needs a lot of effort or money
-e.g. The police have given an undertaking to reduce street crime in the city centre.
-e.g. He was made to sign a written undertaking that he would not go within a mile of her house.
「assurance」这个单词和上面的所有同义词都有本质上的区别，但是这点区别需要仔细体会，这里的「保证」不是指「承诺去做某件事」，而是「承诺某件事会发生」或者「某件事是真的」，而使用的语境是为了让对方不那么担心：
-a promise that something will happen or is true, made so that someone is less worried or more confident
-e.g. You have my assurance that it won't happen again.
-e.g. The manager gave me his personal assurance that the goods would be deliv-ered today.
「guarantee」在这里是「assurance」的近义词，只不过这个「保证」更加坚决，使用语境和后者类似：
-a very definite promise that something will happen.
-e.g. With any diet, there's no guarantee of success.返回搜狐，查看更多