TASK DEFINITION: Generate the answer for a given question. The question requires common knowledge of English. Make sure that the answer is in detail, long, consistent with the context, and requires general knowledge of English. To be less repetitive, please vary your language for each question. Give a proper explanation to answer, and if necessary, provide the definition of various terms. And conclude your answer if it's long. If you have used other resources (e.g., Merriam Webster's.) to answer the question, include citations in your answer. You don't need to paraphrase the context of your resources, but make sure that your answer is consistent and complete.
PROBLEM: When a user wants to delete something on a website, I would like to display a message for him/her to confirm. Which of the following is the grammatically correct way to say so? Are you sure to delete this item? or Are you sure you want to delete this item?.

SOLUTION: Are you sure to delete this item? Sure means 'certain, without doubt'. Therefore this asks if they are definitely going to delete the item. This isn't something to ask the user; if anything it's something for the user to ask about the program; 'will it definitely be gone'. Are you sure you want to delete this item? This asks not about what will happen (which is a question about the program) but what is desired (which is a question for the user). This is the one to go for.

PROBLEM: In my language, when I write an email to my professor, boss, etc, there is a greeting part in the first part of email right after 'Dear prof. ...'(in my language of course), e.g. 'How are you', 'I hope everything is alright' and so on. But I don't have any idea how can I write a proper email with such a greeting in English? Or do I have to ignore it because the email is kinda formal?.

SOLUTION: I almost always start formal e-mails with Dear Professor _, I hope this note finds you well. Some guidelines will suggest ending your salutation with a colon rather than a comma, but in many circumstances a comma is acceptable. If the person's title is 'professor,' you should spell it out (not 'prof.') and begin it with a capital letter when it precedes the person's name (as it would in your example). 'I hope this note (or letter) finds you well' politely establishes a friendly connection between you and the recipient of your letter and in most circumstances is a great way to start it. Especially if you're asking for something, it's good to indicate your concern for the person you're writing to. For the same reason, it's a good idea to end the letter with a phrase or sentence that will similarly show interest in their work or their well-being. 'Best regards,' is fine, but if you can tailor it in a way that's a bit more thoughtful, it's better. 'I hope your book/project continues to go smoothly.' (This can be followed by a 'Best regards.') If this is a person you don't know, you may have to settle for a generic 'Best regards' alone.

PROBLEM: This phrase is all over the internet. They will say that something is free as in 'free beer' and free as in 'free speech'. I have never really understood this. Are these the examples of two different types of 'free'?.

SOLUTION:
Wikipedia on Gratis versus Libre: Gratis versus libre is the distinction between two meanings of the English adjective 'free'; namely, 'for zero price' (gratis) and 'with few or no restrictions' (libre). The ambiguity of 'free' can cause issues where the distinction is important, as it often is in dealing with laws concerning the use of information, such as copyright and patents. And further: With the advent of the free software movement, license schemes were created to give developers more freedom in terms of code sharing, commonly called open source or free and open source software. As the English adjective free does not distinguish between 'for zero price' and 'liberty', the phrases 'free as in free beer' (gratis, freeware) and 'free as in free speech' (libre, free software) were adopted. [...] 'Free software is a matter of liberty, not price. To understand the concept, you should think of free as in free speech, not as in free beer.' Richard Stallman Emphasis added.

