I've recently begun studying Chinese independently. My school doesn't offer Chinese classes, so I've been using the vast stockpile of free internet resources. Quizlet for studying and learning the pronounciation (Quizlet's speak function can handle 汉字 and I check the pinyin tones on each word I put on a list with tiktionary to make sure I'm learning it right. Some .pdf files I've found for practicing written Chinese that have practice squares and stroke order guides. ETC... I think I'm studying well, but I get tripped up on a few things regarding verb usage... When forming sentences with verbs that have multiple ways to be written, which do you use? For Example: The sentence, "I Study Chemistry," could be written either, "我学化学，" or, "我学习化学。" Both mean essentially the same thing, only difference is that the verb is more specific in the expanded sentence. Does this make the statement more formal and if so, would informal spoken Chinese take preference to the contracted form? Is there is a specific time/situation where one is preferred? I need an answer to this as soon I can find one, because this seems to happen with just about every verb I've learned so far, with the exception of a few like 是. Like the verb for to know/to understand/to recognize, would you use, "认, 识, or 认识?" “我认化学," "我识化学," or, "我认识化学?" Please Help! Thanks in Advance!

I notice 起来, 下来, 出来, 过来, etc. often do not have literal translations in English. What is their function? I'm not refering to their meanings of "come down," "go up," etc. I'm talking about when they appear at the end of a sentence and don't have any specific English translation. How and when should they be used? I think there may also be other examples besides the four that I mentioned. Thanks for your help.

How do you say good day in Chinese?

In Mandarin Chinese, 從前, 以前 and 本來are adverbs referring to a past state/action but how does one determine which one is most suitable to use in a sentence?

Today we went over the grammar structure "V着 V", where the first verb is the accompanying verb and the second is the main verb. For example, "我听着音乐做功课。“, which means something along the lines of "I listen to music while I do homework." Or at least, this is my understanding. To say something like "I sleep with the door open", however, you say "我开着门睡觉“, correct? But according to my understanding of the above structure, this would mean something along the lines of "I like to open doors while I sleep.", since ’开门‘ means 'open [a] door'. While this is a little ridiculous, it made me a bit interested. For verbs like this, how would you say something like "I like to open doors while I listen to music", or something along those lines, if that is correct? Just curious if the grammar allows for this, or if it is ambiguous/unclear. Thanks a lot.

What does this mean in English? Zhōngwén yào jiāyóu ó ~

how do you say 'they' in Mandarin, I learned it as 'tāmen' but my friend says that's incorrect, now I'm confused. Please answer only if you're fluent in Chinese, no Google translate -_-

What does this mean? 请把出国旅游以前得办的事，得准备或者得带的东西写出来。 I understand it has to do with planning a vacation, its an exercise in my workbook that goes along with pictures but I'm not sure what to do... I translated all the words and tried to put it together but I'm still not understanding.

Please, I would like to know if any Chinese people or someone who may be studying chinese could tell me what does this expression mean. I've searched in many online translators but I don't seem to fully understand it. It's quite important for me to know that so I would be really glad if you could help me! Thank you for everything!