English is certainly one of the hardest languages to learn, although to a native English speaker trying to learn a foreign language it may not seem that way. The problem is, English isn't just one language - it's a composite of different bits and pieces randomly borrowed from other languages, and each of those bits and pieces brings its own rules that don't apply to the other bits and pieces borrowed from elsewhere. I thought of a good illustration of this, and thought I'd share.
What do these words have in common? atypical, abnormal, discomfort, imperfect, incomplete, unusual. They each start with a negating prefix, which can be removed to get a word with opposite meaning - but there are six different prefixes here, all of which mean the exact same thing.
Now compare that to this list: acorn, absorb, disaster, imagine, internal, underneath.