Hello, and thank you for answering this question.
My name is Victor and I'm from Bolivia. I have the following question:
Is it common in american english to drop r's when reading? I have heard sections of Harry Potter (the audiobook) in the american version. And somehow I noticed that the reader drops r's, and I know that american english speakers generally don't.
It really depends where in in the country your are.
In New England, the r's after vowels often were very faint or dropped all together. My name is Barb but after living there for 15 years, I answer to "Bob."
In other areas, you will find the final r sound in words that end in "er" sound like "uh" - mother is like "muthuh."
That's why I often laugh when people say they want "an American accent." There are dozens. (Same with a British accent.)
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.