Not the same at all. A swish is a conglomerate of two words, if I'm not mistaken, which is "swipe" and "swoosh," and the word is generally lower pitched, as well as not as shrill (sharp) as a whistle. A plane can swish by, but not "whistle" by. A whistle is a sound made by someone, and can not be an action of "moving by with a sound."

A good answer above, but from a grammarian point of view, there is more to it than that. In fact, it's very similar to the "less" vs "few" rule. You use "many" when the item is a noun that can be counted. For example, "money" is not countable, so you cannot say "I have many moneys." (Of course you COULD, but that indicates many TYPES of money, and not "a lot" of dollars, for example. It would have to be money from other countries). This leads to my next point: you use "much" when the item is not countable. Seeing how you can't really say (without making much sense), "I have three monies," you use "I have much money." Similar examples would be the use of the word "candy." "Candy" is a collective, or a countable, concrete noun. You can either say, "I have much candy," (to which you could reply with "how much candy do you have?") or you could say "I have many candies," (to which you could reply with "how many candies do you have?"). If the word is collective, which means that it contains a number intrinsically (per se, if you will), then you use "much." If the number can be counted (1, 2, 3, etc) then you use "many."

You need to be more specific. No one can help you because no one knows what you are talking about.

It means that the action was completed. For example, 我吃好了。It means I finished eating. The function is to show that the action was successful and reached the end.

I believe vocational courses have to do with a specific job. In other words, courses that provide skills for a particular specialization. As for non-vocational, well, that's relatively obvious: courses that do not provide anything for skills of a particular trade. If it were up to me guessing the difference, I'd say it's similar to electives outside of a degree (ex: Chinese taken while being a major of a technology degree would be considered non-vocational).

Prepositions shouldn't be hard to work with because they have to do with space and time, and you use whichever you think is best. There is no "solid" rule for prepositions, and anyone who says otherwise does not understand English grammar. For example, you can live in a garden, or you can live on a garden. You can live around a garden, on top of a garden, or below it. Either works, since it's anchored to the meaning, rather than strict grammar (yes, it still follows grammatical rules). For "in," you say "in" when you are referring to something that has a clear border, or has boundaries that can (but do not necessarily have to) be in three dimensions, and perhaps when an object is surrounded from all sides. That's the general idea. Now, if you're having trouble with this, this can only mean that you do not understand words and their spatial relationships with other words. Think of the word "country." Would you say "on" your country? You could, but the object must be physically on top of a country. A country is rather abstract, though, so it would be rare for anyone to say that except in some specific cases. Would you say "about" your country? About indicates something being in the vicinity, or at the edge of something, but not at the spot of it. Does that make sense? No, it doesn't. Your other example is rather a common problem people have. "Help" is special in that it functions almost like an auxiliary verb, even though it is nothing but a verb. "Help to" is simply out of style. It has become more habitual than anything because it is understood so well. For your own reference, you can look at this website regarding help vs help to: https://sites.google.com/site/sowhoisscottdraper/home/help-vs-help-to

Yes, both are grammatically correct. No mistakes.

Closely correct, yet here are "better" ways (and more grammatically correct) of writing those two sentences. First one: Do I have to mail the original documents to you after sending the faxed copies? Second one: Or can I submit the original documents when I arrive to the U.S?