Do you know about Quora? It’s one of the best social networks in terms of questions and answers. Needless to say, there are numerous questions and answers about the English language. This is a particularly good example:

QUESTION

What are the most annoying grammatical mistakes in English that native speakers make?

ANSWER

There are three grammatical mistakes that are particularly annoying. One is the use of the nominative when the accusative is correct. People know that it is correct to say “Fred and I went to the cinema”, and conclude, incorrectly, that one should therefore say “She gave it to Fred and I”, while you should say “She gave it to Fred and me.”

The second mistake is the use of “less” instead of “few.”  Some native English speakers seem to think that “few” or “fewer” is pretentious, so they end up saying “less people” as if people were a countable noun.

The third: the vice of writing (this is a written-only error) “he would of done...” instead of “he would have done.” This is because is you speak quickly, of is pronounced like have.