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.
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Question: Is it correct to say 'Wish you a happy weekend' or should I say 'Wishing you a happy weekend'?.

Answer: Neither Wishing you a happy weekend nor Wish you a happy weekend would be used in normal conversation. As others have noted, spoken parting platitudes at the end of a week are normally started with have, such as: Have a good weekend Have a nice weekend etc. Change the adjective to be what you think most appropriate for the situation. On the other hand, if you are signing off some correspondence, such as an email, then Wishing you a happy weekend is more appropriate. Similar constructions include Wishing you a happy birthday Wishing you a merry Christmas Wishing you well To use *Wish you a happy weekend you need to add I to make the sentence grammatical. i.e. I wish you a happy weekend. A notable exception to this is the common postcard sign off Wish you were here where it is idiomatic to leave out the I.

Question: I am looking for a word or phrase which can be used in the sentence: It is a rather old, but _________________ technology. The word or phrase should address a technology that is totally investigated, researched in detail, and thoroughly optimised, so there is nothing more to find out or improve.

Answer: Most common term I have seen repeatedly and would thus use is, well established. It is rather old, but well-established technology Note as correctly point out by @Chappo below in this case grammar dictates a hyphen is required since it is a compound adjective preceding a noun. 'science can be leading edge or well established' Wiki Technology

Question: Do the English have an ancient (obsolete) verb for the action of the book opening? For example, in Russian we say otkrit' (open the book), but in the Old slavonic the verb razognuti (to unbend the book) was used.

Answer:
This is a very interesting question. There may not be an old word in English that does what you describe, but it is important to note that the English word 'open' relative to a book meant something different in earlier times. To open a book now usually means to part or spread the cover and the pages into a position so you can read the pages contained in the book. However, books used to be made by folding sheets of paper larger than the page size and they would be sold without trimming the edges, so when you got your new book, it would be 'unopened' meaning that you couldn't turn the pages. You had to 'open' the book with a dull knife (like a letter opener) by ripping along the folds. (This is why some books have ragged edges of the text block, to evoke the memory of those ripped page edges.) The OED has e. transitive. To cut open the leaves of (a book) when they have been left joined along an edge during the making; to cut open (the leaves) of such a book. You will find old books described (by knowledgable book dealers) as 'unopened'. This correctly means that the folded sheets are un-ripped; it doesn't mean that no-one has ever spread the covers and looked inside.