Ash, your post and comments are full of errors, and errors that no English speaker would make at that. That is why even people who think they have learned all of the grammar are not usually in the best position to correct other learners' work. Where you could be useful is explaining some concepts to other Chinese English learners who are at a lower level than yours.

<em>"I didn't expect to have the mistakes in this post..."</em>

Ash: this is exactly why non native speakers of a certain language shouldn't correct posts in this language!

I know that you want to help, but you would never know that you are making a mistake or not, and the learner you are trying to help, might end up copying a mistake you made, that you actually thought it's a correction.

Of course, some native speakers make mistakes! But that doesn't mean that non natives should step in and correct in a language they are still learning, but it definitely means that those native speakers who know that they are not competent in their own language should stop correcting others.

Phil I never "pretend" to do anything, especially when I am addressing non native speakers. I wasn't sure what his meaning was. To be sure Ash's English is at a high level, and he is certainly to be commended for his achievements and hard work, however that is not the issue at hand. He very specifically asked me to correct his English, and I did so in the same way I would for anyone else who has asked for my help (which I had not thought was necessary as this is not a notebook; Someone who claims they can correct others work should surely have been able to locate his own errors.)
The issue he has is that he doesn't like people choosing the assistance of native speakers over him, when those learners not only have every right to do so, but are also very wise to make such a choice. If someone is saying they are capable of correcting the work of others, they must be held to the same standard as a native.
As he himself said in different words, he who makes uncorrected mistakes is doomed to make them again and again. It then follows that if he teaches those mistakes the problem is compounded. Even worse, he, and many other non native "experts" in the English language, often tell other English learners that perfectly good parts of their writing is wrong. They don't ask themselves "How can best I use my skills to help others?" (both I and others have given some suggestions) their thought is "I want to do what I want to do" while also trying to prove they are better than natives and disparaging them.

It's also important to understand that the kind of mistakes native speakers make are often considered “small” mistakes in English classes. When I was a high school student, writing “your” instead of “you're” or “its” instead of “it's” would obviously set back my score , perhaps 0.2 or 0.5 point, depending on the test. Such mistakes wouldn't directly cause me to fail my test though, especially because they are the sort of mistakes even a native speaker might make.

Using slang like “I'm gonna” or “I got” would take my score down at least a full point, though. Sentences like “Needn't to take it serious” or “The octopus is one of many creatures, whose look is unappealing, are actually quite tasty” would also have a large negative impact on my score. Such mistakes immediately give you away as a non-native.

As long as you're not at a (near-)native level, I think it's best to refrain from correcting others unless you're 110% sure of your answer. One thing all of us should do, in my opinion, is flag “incorrect corrections” when we see them. It might make native speakers aware of their mistakes, but more importantly, it can prevent unnecessary confusion for students. It can even be done in a private message, if you're worried you'll embarrass the corrector.

If you ask me why a Chinese sentence should be put that way, I can't tell you the reason even though I'm a *native (using quote marks implies that you are not actually a native speaker, I assume your profile is not a lie) Chinese speaker.
SO what!!! I can tell you why your sentence is wrong because it doesn't sound right to me, and that's all. I know English even better than Chinese even though I can't find a proper word to express my idea in English sometimes. I can *tell you a bunch of grammatical terms to explain why your sentence is wrong because I'm studying English literature at university level. I can tell you what is *an oxymoron, allusion, onomatopoeia and so on. (these are terms used to analyze literature, they are NOT grammatical terms) ("I can tell what an oxymoron ... is")
find (present because you continue to feel this way) it so disrespectful to ignore someone giving you helpful advice on how to revise your sentence just because he is not a "native" speaker. I don't mean to *offend *native speakers. If it does, I apologize for what I wrote.

---(A native English speaker who doesn't know what an oxymoron is can look it up in a dictionary and 5 minutes later tell you what it means too.)

Don't worry everybody, arrogance is it's own reward.
Example of stupid grammar:
"The left and the right glove of Susan fell to floor." This sentence is perfectly grammatically correct, but if you say it or write it native speakers will laugh at you. It should be:
"Susan's gloves fell to the floor."