I think the most appropriate option here is "Until I explained her the situation I felt guilty. From the grammar perspective in such sentences you could use past perfect to describe the action which occurred first. For instance, I had finished my meal when she arrived (at first I finished the meal and then she arrived) But in your example at first you felt guilty, and afterwards you explained her the situation. Moreover since you use "until" in the sentence it is oblivious for a reader which action occurred earlier, so you could just use past simple for both verbs.

Actually that means " nerves made of iron" which is a way to describe a mentally sustainable and patient person.

A simple introduce

My name is July. I'm from Сhina, but working in Japan now. I want to study english, who can help me with that?

Learning english...

Hello everyone!! I'm learning english and attend an english academy every day, because I want to pass the B1 exam. I successfully passed the exams in my highschool, but now I realize that I don't know english as good as I believed. My language teacher is an engish native speaker and she is a good tutor (try to avoid repetition). Today she asked us what would we do if we would win one million of euros? All my classmates didin't know what to say, so she started to laugh and our homework is to write a story about that.

Hello I come now (not sure what you meant)

Hello, my name is Nihat Aslan. I live in Mardin, which is located in southeastern Turkey. I am single and work as a primary teacher. I am twenty-seven years old.

1) It depends on the context you use. For example, you could say "the computer I saw yesterday" (the specific computer) or "I need a computer to check my email" (a = any computer, one computer) or "I like my computer" (no article since you use a possession word) or "Computer is the great invention of humankind" (computer in general)

Hi, please help me ;D

Hello, my name is Karyn. I am 31 and live with my boyfriend whoes name is Francesco. I am originally from Brazil, but currently I live in Valencia which is a major city in Spain. It is a beautiful city with beaches and mountains. I like living in Spain, but I miss my family and friends. The good thing is that I can talk with them using Skype, Facebook or phone. I speak Portuguese and Spanish, and I want to expand my knowledge in English in order to read such great works as Whitman's poems. I hope we could  become friends and share our experience.