Which one is natural? I'm offering something to eat, etc. If I say; If you refuse, or I'll be offended. If you refuse, and I'll be offended

What‘s your name？  

Which one is OK? He was lying to me the whole time we dated.. He was lying to me the whole time we were dating.

Which one is OK? It's a pity you don't stay. It's a pity you're not staying.

Can I use these interchangeably? He turned out he's married. He turned out to be married.

HELLO ALL OF YOU I WISH I CAN FIND SOME FRIENDS HERE. I WANT TO PRACTICE MY ENGLISH

Could anyone help me with the following sentence? "He had not written a line since he arrived". As I understand first he had arrived and then he didn't write anything. I think that "He had not written" is a posterior action. Could you explain why it's not possible to write the following way? He didn't write a line since he had arrived.

In formal writing, I often see structures like “It is essential that he be informed” instead of “he is informed.” Can someone explain how the subjunctive mood works in English and when it’s appropriate to use?

When someone say “You’re quite flexible “ Does quite mean a little, or a large degree or completely ? Or it could mean all of them and I just have to guess lol ?