I taught a lesson yesterday on phobias, as well as the present perfect tense. I planned elaborately as how to best to teach the word "phobia", using pictures, miming, and even a short script.
It turns out that the Russian word for phobia is fobiya. However, Russian doesn't have a present perfect tense, so my planning was only 50% completely useless.
Other English words that need not be taught in Russia include:
Impotent (important, however, is an entirely different word)