At or in? We say : He is weak at English Or He is weak in English And what is the rule if there is any? Thanks in advance

Issues with Italki I'm using Italki app for mobile, and I don't get any notifications about comments, corrections or even new messages, so I need to go check on manually each time, in comments and corrections corner. I wanna just know if that's how things go on Italki, or do I have to fix something on this app settings??

Which one is correct? Which one of these two sentences is grammatically correct? 1: I like to always be prepared 2: I like to be always prepared Thank u in advance

if I were / if I was ? I wish I were / I wish I was ? i found these two sentences, where the verb to be is used differently with the pronoun " I ". I wonder why? do you have answers ? here are the sentences : 1) I don't have a lot of money, I wish I were rich. 2) I wish I was on the beach. (I'm in the office now). Thank u in advance

aren't I or am I not ? I've heard some native speakers use this form of tagging questions (aren't I), so I wanted to check if it's really in use, despite i still can't understand how could (are ) be used with ( I ) without being a grammatical error ? 

(you and I ) or (you and me) ? it's a bit confusing in a direct conversation, for a non native speaker, to choose the right combination of words, ordered in a way that might make him/her sound natural, even if they got a high level in English, with good grammar and vocabulary. so my question is : is there any way, or trick or anything alike that could help choosing the right combination of words that work together and make the speech sound right to the ear ? I.e : *high price and tall building ( could we say High building?) * black n white ( white and black ??) * left and right or right and left and there's a long list of such. Thanks in advance.

do you have any skills or hobbies besides your main job? I am a vet , but i barely treat any animals for now, may be because I didn't open my clinic yet, i'm working now in shipping, I deliver veterinary medicines to vets, and I get my living from it, and spend most of it on constructing my own clinic, I like doing it on my own.
 i've never delt with plaster before, but when I saw that movie in the YouTube, I felt like I could do some plastery alone. So I bought the necessary tools: a drill, some screws ...ect, and the main unit if contruction which is of course the plaster boards.
In the beginning, it seemed quite easy and amazing, but lately, i've become a bit lazy, because it took too long, much more than I thouggt. I kind of started to feel bored and lost, especially when it came to the final part, the part that I had to close the remaining fistures with the plaster glue or mastic or whatever it's called, just before painting it. 
When I finished constructing it, you don't know how much was I feeling happy, proud, and confident.
no builder nor painter is needed any more, from now I can build whatever I need, i'm an experienced plaster builder now! Those are kind of words I was telling myself by then, I would call it "the victory moment saings" but i'm sure now it won't be a good idea to get through any work alike any other time, because it's not my job after all.

когда можно сказать : Москву, Москве, Москва? when each one of these are used? and what is the rule of changing feminine noun endings from (a) to (o), and from (я) to (ю)

writing is really an extremely hard skill to get !! Hi all. language is a never-ending learning process, I mean no matter how much words and terms you come to know every day, or the improvements in your pronunciation you get, or accent amelioration you achieve that make you think you took a serious advancement, it all actually let you discover how far away you are, and how long the way still to come is. speaking of my experience with English education, I realized recently how vast this language is, even though so many people say it's easy, that anyone can master in few weeks !! that's not true at all, and I can't imagine any normal person able to do so, because I've spent years so far learning this language, not continuously of course, but I've used every source and all means available so I can master it, but my writing speaks of itself, I'm barely understood right? anyway that was just my opinion that could be partly right or totally wrong, it's up to you to judge it, and I'm all ears if you got any comments or correction, some tips of a good writing, or any sort of advise. thank you