Sergey spoke at length about his work today, easily explaining complex and diverse concepts and situations, while making very few mistakes. I say mistakes for want of a better word, because almost all of them are grammatically correct and convey the right meaning, but aren’t quite what a native speaker would say. This is a testament to the extremely high level of Sergey‘s English. And he‘s eager for corrections, often coming up with the right phrase or idiomatic expression on his own. Talking with Sergey is always interesting. He has a remarkable mind.