What is the hardest second human natural language for you? What parts are you having trouble to learn? Which languages can you read without learning?

I'm a Chinese speaker and my second language is English. After I grasped the irregular grammar of English, the most difficult part of English is now the pronouncation, It took a long time before I realized that I pronounced "in" (I pronounced it like "inn"), "programming" ((pu lo ge la ming) or (lo ra ming)), "throw" ((ze low) or (slow) or (low)) and "book" (buuk, heavy u's), why English can't be as easy as Chinese and Japanese.
My third language is Japanese, its grammar is very easy, compared to English, and I can read a lot Japanese, because I know Chinese characters (of course, I understand Chinese characters are the most difficult parts for them).

My 4th most understood language is French, I learned a few words by looking at the signs and boxes.

im telling you, Persain is hard! to say "cat" you say "peeshi" @_@ its so confusing!

The language of Love. :c

Spanish is pretty easy, but that's not the point, I guess C:

I think Chinese and Japanese are a little more difficult because of how the sentences are structured differently than in English. Then again, I only know a few words in Japanese so I can't say for certain. I have heard English is the hardest language because of how different pronunciations can be and the TONS of grammar that entails it. Kudos to those who learn it as a second language. :D

Um... "in" and "inn" are pronounced the same, fyi. |D

Anyway, I would say Japanese. I've only studied a little bit of it, but it's just so darn confusing. I guess because that language evolved on the other side of the world from English. |D

If I had to hazard a guess, I'd say Arabic, Chinese, Japanese, and Korean.

I would say Japanese, as it's a "phonetic language" but it's really not. I mean, most Japanese speakers don't go "desu" or "yoshi", they say "dess" and "yoshh" which is like wtf mate, are textbooks trying to make you a silly foreigner? |D
Also kanji. //ffffrageplz
Swedish is also kinda hard, since it's very rare to find instructional material.

I can easily read most romance languages as I know many Latin roots. French is an exception. Too much phlegm. :\

Japanese has many untold rules at pronouncation, other than the desu, sometimes o is pronounced like the Chinese o and sometimes the English letter O.
I guess I'm going to only write Japanese.

I can honestly say, as a Korean, that Korean is the hardest language for me. Even though I speak a lot of Korean in real life, I often mishear the vowels or consonants of a particular word. I was told by my best friend's sister that if I learn Korean enough, Japanese is like a breeze. I'm guessing if I can learn Japanese, Korean would be much more easier to write and speak. My main problem's pronunciation, I always misspell because I always misread/hear words in Korean. It's quite confusing for me, mind you.

Uh... I think that's all. xD

It is largely dependant upon your mother-tongue. English is a mixture of Germanic language and the Romantic (French, Spanish, Italian, thus named because it is derived from Latin, which was the language of the Romans ), thus for most English speakers, those are the easier languages to learn, as the style of grammar and pronunciation bears some similarities.

Likewise, I'm guessing there are probably more similarities between Korean and Japanese than Japanese and English.

Personally I pick up languages easily. I would say overall English (tho my native language) is probably the hardest for the world as a whole. But Personal spanish is hardest for me pronounciation-wise because i cannot roll my Rs :( I also speak french currently learning japanese and hope to start chinese next summer or fall.

My mom said Greek is the hardest, even a language professor will make mistakes.

(look at how Hong Kong people speak English: http://en.wikipedia.org/wiki/Hong_Kong_English)

I can't roll my tongue either in Spanish too Aurore =c=

I guess anything on the other side of the world would be difficult for anyone to learn. European people having difficulties with Asian languages, and vice versa, which makes sense because of the different language roots. Off topic: I learned how to count to 500,000,000 in Spanish today |D

Well, I find Japanese hard to learn. I find it ALOTH hard. I have been trying to talk it but, still no hope. -3-

And, I have NO idea how to read it.

But, I can tell you one thing: I speak French and English plus, I go to a French school. 

The hardest language that I've tried my hand in, in my opinion, is Russian. I'm studying it now and have been for a while, but it's very easy to make silly mistakes (especially as I'm a native English speaker).

Example: I don't make this kind of error that often any more, but as Russian uses an alphabet called cyrillic, and some of the letters look the same as ones in the Roman alphabet but mean different things (cyrillic B meaning V, cyrillic p meaning R, etc) it is not difficult to stumble when it comes to pronouncing things. I'm notorious at the former, getting my Bs and Vs mixed, and it's one thing my Russian teacher keeps heckling me about :b

As for languages I haven't tried learning, I hear Chinese and Arabic are particularly difficult.