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.

How can I explain to people that the phrase off of is grammatically incorrect? I've heard this phrase used a lot, especially by Americans (though they aren't the only ones). In my understanding, off of should usually be replaced by off, as in, I took the book off the shelf as opposed to I took the book off of the shelf Am I wrong? Or is there perhaps some simple way I can explain this to most people?.
I don't know how you can explain to people in general that it's grammatically incorrect, but here is one idea: when you go to a James Brown tribute concert and the singer says 'Get up offa that thing' what you could do is to trounce the security guards, climb on to the stage, pounce onto the singer, grab the microphone and say 'In fact you should be saying not 'get up offa that thing' but 'get up off that thing' since 'offa' is grammatically incorrect.' I'm sure everyone will thank you for your grammatical corrections. Being serious for a moment though, it's very difficult to decide what is or is not 'grammatically correct'. E.g. in the UK we say 'outside my house' but US people often say 'outside of my house'. How can you actually decide which of these two is grammatically correct? Unfortunately it's not possible since English grammar is not a science like physics but merely a description of what people actually do, and that has changed very significantly over the years. If I was teaching someone English I would definitely say 'off' is correct and 'off of' is wrong, but this kind of decision is based on intuition, based on the usages of educated native speakers.

I see a lot of times when something is a politically-oriented scandal that the suffix gate is added to the end of the word the scandal revolves around. Examples include: Watergate Weinergate Valijagate (Spanish for 'suitcase-gate') I believe that it originated during the Watergate scandal, but I don't know why the suffix gate was perpetuated to other scandals. Is there a name for this literary mechanism of using part of previously popularized term to elicit a comparison or similar connotation?.
This is a great example of a back-formation: a word is treated as if it were composed of prefixes or suffixes, then taken apart (incorrectly) and remixed to form new words. Another famous example is cheeseburger. The burger suffix is incorrectly taken from hamburger, which is a dish from Hamburg, not a burger made from ham. Watergate was a big enough scandal, and sounds enough like it's composed of Water and gate, that the suffix has been back-formed into plenty of other scandal names.

In math, we use the term series a lot, and there are many types of series. How should I craft my sentence when I have three different ones in mind to talk about? Should I settle down for a less mortal alternative of 'list of series' or something like that? The existing question on The possessive and plural forms of 'series' suggests the usage of series'. But is that all? If that's the only solution, then could you please explain the usage of apostrophe symbol at the end? Is that a plural marker or a possessive marker, or both?.
Series (like deer, salmon, and sheep) is pronounced and spelled the same in the plural as in the singular. If either the singular or the plural is used as a possessive, an apostrophe is added to show that in print, though there is no pronunciation difference in speech. Thus, The series doesn't converge. (singular) The series don't converge. (plural) This series' limit is unknown. (singular possessive) These series' limits are unknown. (plural possessive) More examples can be seen here.