A wrong pronunciation..

In Italy there's a famous English teacher who published a course of English for Italian speakers. Today I listened to a short interview of him on a national radio station. The speakers talked with him how Italian people easily get wrong when they say some English words because most of the time we don't pay attention to the right pronunciation.
They made the example of the word: "beach". We use this word very often, especially when the summer arrives, but we always pronunce it with a short "i", so that a sentence like "I'd like to go to the beach" could sound different.
It happens the same with the word "sheet". The English teacher said that once one of his students, while he was talking about how he spent the weekend, would have liked to say "I put a sheet on the beach" but at the first listening it seemed he said something else.
In the end the English teacher reminded us not to use the preposition "in" after the verb "to come" because, if we are at office, we might cause awkward situations.