It is a fair question, but the answer to it is not easy.The hardest part for me in the English language are prepositions. That's really what defies analogy with the native Russian. Where we expected an excuse, it is no reason. For example, to marry smb why in English there is no preposition. We all just. to marry someone. The preposition like should be "on", but nothing like this.Second, no less difficult problem of the English language is the polysemy of words. When you open the dictionary to find the translation of a word, just tired to read the list of meanings of the word. For example, the word cast. Still can not fully understand how to use it. How, then, to learn words and expand your vocabulary? The solution is to remember in the context of a work. That is, again, one has to read and listen to the English language