Thank you! How will you explain when employer in requirements ask "..to speak English fluent and idiomatically" ? What is level or smth else to speak such way?

If I were you I would concentrate on the use of phrasal verbs and not idioms. They would be more helpful as we use them all the time. A very few examples. To wake up. To get off. To take off. To give up. To put on.

Just don't go too big on street talk because it sounds weird if your language is otherwise not very strong. I'd say read the lyrics of the songs you like, most of them have idioms. Or do a search on Google for idioms, you'll find a ton of cool sites that list idioms. To answer your question as you asked it: - not the sharpest knife in the drawer (not smart) - having bigger fish to fry (more important things to do) - until the cows come home (a very long time) - take a raincheck (love to do it but would prefer it some other time, from baseball games when it would rain and the game would be canceled) - no room to swing a cat (very tight space) and speaking of torturing cats (no, I do not condone it!!!) - more than one way to skin a cat (there are several ways to do something) Hope this helps!