why can't you say..........

Because it is not an ongoing action. You know him or you don't. The ongoing action is "get to know". So you can say "I have been getting to know him for 2 years."




"Since five years" should be "since five years ago" otherwise it doesn't refer to a time in the past. When modified like that it makes sense, but it sounds strange.

A better way to put it is: "I have been studying English for five years."

A simpler and better form of the first sentence might be "I've known him for two years."

I agree, but would like to note that the meanings are different so it depends on what you are trying to say.

I note your note.

Why won't my computer do emoticons on A2K any more? Just wondering.