Hi. By searching the italki database, http://www.italki.com/search/questions/q/assure.htm we are able to check some previously posed questions, http://www.italki.com/answers/question/57618.htm http://www.italki.com/answers/question/60777.htm and you may look up those webpages for references regarding the differences between "assure" and "ensure". Regarding the term "promise", here is some information of its definition, http://www.wordreference.com/definition/promise Additionally, 我向你保證 (甚麼...) = I promise you (sth.) Good weekend. / 祝　週末愉快。

Promise, assure, ensure are all similar. BUT...there ARE differences.... Let's look at some examples, first: 1. I promise you I will be home on time./ I promise (you) I will be home on time. 2. I assure you I will be home on time. 3. I ensure that I will be home on time. What defines the basic differences is the object of the verb. An object (direct or indirect) is what directly or indirectly receives the action of the verb. Difference #1: The object of "promise" is often a person or understood to be a person. Even if the person is not stated, it is still understood. (I promise HER, we promise THEM, I promise (YOU) that) Difference #2: The object of "assure" is often a person. Where I am from, you rarely use assure without the object of a person following it ("I assure YOU, they assure HIM, we assure HER...) *"Assure" is much less common than "promise." Difference #3: The object of "ensure" is often a thing or the action promised. ("I ensure THAT I WILL BE HOME ON TIME", or more literally, "I ensure THE ACT OF me being home on time") Now, the differences above are based on common uses in English. They are still interchangeable, but you will most often see them used in the above ways. Source: self (American English)

Yeah, the sources he provided are correct. Let me show some examples: I assure you, everything will be ok. I will ensure your safety. I promise I will write back tomorrow. This idea holds a lot of promise. They are small differences.

They can all be used as the same, but a promise is also used in the context of a contract. There is not really any difference you need to worry about though.