"I know that programming language"

1. You'll never manage to learn the only programming language. You don't know language unless you have something to tell about it. There's nothing you can tell about the language unless you can compare it to anything else.

2. I don't understand the people who only know either Java or C#: both these languages (platforms) are too similar to atone for one's familiarity with only one of them.

3. I go mad when someone tells me that I have to think specially, write specially and build specially when I use "language A", because "it's not the same what you always do in your language B". Especially, when the person who tells it to me is not both p.1- and p.2-compliant.