Conditionals: We use “would” to create the conditional of all other verbs (not “can” and not “must”) to express uncertainty in actions (unsure if they will occur), to be polite in making requests, to ask others about their desires, or to decline invitations politely. I would buy a home if I won the lottery. —It is something I think I will do, but I am unsure. I would like some water, please. — I am politely asking for water. Would you like a coffee?—I am asking about another person’s desire. I would come, but I already have plans.—I cannot come, but I am telling you politely (here, I am also expressing that it is an action I will perform in other circumstances, such as when I don’t have other plans, but like my first example, I am unsure) We use “would have—(would + present perfect)” to express past finished actions where there was a possibility of their occurrence, but that something else prevented those actions from occurring or being realized. He would have come, but he was busy. —He wanted to come, but he was not able to. If I had studied harder, I would have passed the exam. —There was the possibility that I pass the exam, but I did not pass because I didn’t study hard enough. “Would” can also be used to express a “future-action in the past,” that is, when we describe a past situation in which we want to express that a certain action will occur in the future. (In some cases, the action may still be unrealized, and so there is still uncertainty or doubt, but not all cases) Mark told me that he would come. —Mark told me( in the past), but he was not “coming” in that same moment that he spoke to me. “Where is Mark? He’s not here yet.” “I’m not sure, but he told me he would come.” —He said, “I will come,” but he has still not arrived. The action here is UNREALIZED. “Oh, look! There is Mark, he just arrived!” “Yeah, he told me he would come.” —He said, “I will come,” and he has just arrived. The action here is a future in the past that is REALIZED.

I think of "ability" as the primary concept involved with "can" and "could". Ability overlaps into permission and possibility, and perhaps many other things. I think of "intention" and "certainty" as the primary concepts involved with "will" and "would". These overlap with desire, and perhaps many other things. The difference between "Would you do me a favor?", and "Could you do me a favor?" is that the first is more polite (although the second is not rude). The reason for this is that if the person replies "No" to the second, he is saying he is NOT ABLE to do the favor. That places a big burden on the person because the only way to avoid doing the favor is to claim lack of ability.

Hi there! The difference between "would" and "could" lies in their implications and contexts: Would: Typically implies a willingness or preference. It's often used to ask about someone's desires or to offer something politely. Example: "Would you like some tea?" This implies a polite offer or inquiry about someone's preference. Could: Implies capability or possibility. It's often used to ask about someone's ability to do something or to make a polite request. Example: "Could you pass me the salt, please?" This implies a polite request for assistance. Your sentence patterns are correct and polite. They're commonly used in everyday conversation and are appreciated for their politeness. It doesn't necessarily sound fake; it's just a polite way of interacting with others. However, sincerity in tone and demeanor can enhance the effectiveness of politeness. So, it's not just about the words but also about the way they're delivered.

- Would is useful for hypotheticals. 假设。 Would you marry me, if I asked you? - Could is useful for ability. Could you talk louder? Your sentences are fine :).

Hi, Both "would" and "could" have multiple different functions, and therefore it's not really possible to give a complete answer to your question "What's the difference between [them]" - the answer would exceed the maximum length allowed in this section. You need to take some time and study this in more detail with a good book, website, podcast, teacher. It usually takes people a while to do this. However, I can try to answer in relation to your two example sentences. In sentences such as "Would you like a Sth/to do Sth?" the word "would" relates to willingness, and means "Do you want Sth/to do Sth?". It is true that"would" is a polite form. Although in many cases people aren't really thinking about being polite, they just use this sentence pattern as a habit. You are right, in your example sentence "could" is the polite form of "can". You ask if this sounds genuine. Because you added another phrase which is used for politeness ("be so kind as to") you have created an extremely polite sentence. Whether or not this seems excessive depends on the context. It's not wrong, but maybe it does seem a bit unusual because I imagine that in this example the person you are communicating with has the job of telling you information and probably wants to do it. We normally use "Could you be so kind as" in formal writing, so I would only say it in formal situation when I think that the other person might be reluctant to do what I ask, or when I have asked them several times and they haven't done what I have asked (it's a sort of signal that I am about to become less friendly!)