трудно учить правила языка, но если

трудно учить правила языка, но если ты не собираешься писать письма на русском языке, то тебе эти правила не нужны.

Результаты (английский) 1:

It is difficult to teach the rules of the language, but if you're not going to write a letter in English, then you don't need these rules.

Результаты (английский) 2:

difficult to teach the language rules, but if you're not going to write letters in Russian, then you do not need these rules.

Результаты (английский) 3:

It is difficult to teach the language, but if you do you're going to write letters in English, so you'll these rules are not needed.