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.

Q: Are shit, shat, and shitted all correct and fine to use as the past tense of shit? After a little bit of searching it seems that they are, with shat being Old English. Is any form more common in British or American English? Erik Kowal claims that shit is mostly American English and shat British English. [M]ost Americans don't change the verb form for the past tense of certain short verbs ending in -it. So fit, spit, shit, slit and pit are thus formed both in the present and the past tense as far as Americans are concerned, whereas people from Britain would almost always use fitted, spat, shat, slitted and pitted for the past tense. What about shitted?.

A: The OED's etymology for this word is: The form shite represents OE. *scitan, pa. t. *scat, pa. pple. -sciten (in be-sciten), corresponding to OFris. *skita (NFris. skitj, pa. t. skad, pa. pple. skedden), MLG. schiten, Dutch schijten, OHG. scian (MHG. schian, mod.G. scheissen), ONor. skita (MSw. skita, Da. skide), f. OTeut. root skit-. The now more common form shit is influenced by the pa. pple. or the related sb. As far as modern/current forms go, it says that: The present tense is either shit or shite. For the past tense, the OED gives all three of shit, shat, shitted as current. So the answer to your question is yes. For the past participle, the OED provides only shit and shat, with shitten last appearing in the 19th century. That means you won't find any one 'correct' answer. Because those variant forms are all used natively by speakers born to the language, all are therefore 'correct'. Use whatever you please.
****
Q: Someone told me that I shouldn't use the phrase discuss about, but should say, instead, discuss (the topic). He said discuss means talk about and using discuss about is like saying talk about about, which is redundant. Is he correct? Could somebody elaborate on this?.

A: Your friend is correct. You can discuss something, or you can talk about it, but discuss about is redundant for the reason you identified. discuss: to speak with another or others about But if you want to use the word about, you can have a conversation about, confer about, debate about, or even have a powwow about. Most of the other synonyms for discuss don't take about, nor is it needed to converse (or debate).
****
Q: So I thought I'm sure about this and my instincts say that: 'If anyone has seen them ..' would be right but then again when I said it like: 'If anyone have seen them ..' I started thinking which one would be the right one. Can you please guide me through which is the right one and why? P.S. English is not my first language.

A:
It's 'if anyone has', because 'anyone' functions as third person singular. It probably just seems right to use 'have' because you would for any other number or person.
****