'The' is not used for 'uncountable' nouns, like water, or in this example, nature. 'I have one water' is wrong and has no meaning because you cannot count water; is it the same with nature. However, 'universe' is countable! even though there is only one (that we are aware of!) It is the only universe, but it is a discrete entity, so we can count it, and it does take the article 'the'. For the same reason we use 'the' when talking about 'the Internet' - there is only one, but it is countable - but we don't use 'the' with the word 'cyberspace', which refers to the concept of an area where computers operate the Internet, and is not countable.

In case you were curious, in America, we don't use either of these terms, both jobs as described by Mark would be called a 'traffic cop' in everyday American English

This is a very strange sentence, and it is nearly impossible to know the meaning without seeing more context. However, I was able to find the context, a short piece of writing on this page of this book: https://books.google.com/books?id=_-PzdXhnhLIC&pg=PA158 In this piece, the author is talking about the long and difficult process a writer may take from a small and vague inspiration all the way to a completed book. So the author is using 'yeast' in a very artistic and unusual way - I have never seen the word used like this before - to mean 'inspiration', for writing, in this case. This was only clear to me from reading the entire paragraph, which is about authors who write a book then still can't get the details of their story out of their head, like there is something about their own writing they still haven't discovered. The literal meaning of 'yeast' is a substance used that is necessary to make bread. So here, 'yeast' is a metaphor: in the same way that yeast is used at the beginning to eventually create bread, an inspiration is necessary at the beginning to eventually write a book. The way that the 'yeast' (or inspiration) outlives the book, is when the author cannot move on from the ideas in the book, and they become an obsession. Again, this is not obvious from that one sentence alone. Reading the entire paragraph was necessary for understanding this one sentence.

Two (tǔ)? Or is it eleven (十一)?

The first month of my college life .

Recently, I have been busy participating in various kinds of school organizations, including broadcasting and magazine organizations

(with 'recently' it is better to use the past imperfect tense with 'have')

I'll try my best to improve myself in this university.

('Enrich' is not usually a verb one does to oneself, so I changed it)

Although I don't like some classes, especially advanced mathematics ,I won't give up easily.

('Pretty' does not fit in this sentence.  Sometimes 'pretty' can be an intensifier, like 好 in 好热, but this only works before 形容词)

Sometimes I miss my grandparents, sisters, and brothers a lot, so when I do, I usually look through their photographs .

(You used 'sometimes' and 'usually' in the same sentence - this is okay! but if you do, each 'time word' has to be part of a phrase that could be a complete sentence by itself.)

I love writing, which will be how I spend the majority of my free time, but I realize that I have no words to write down over time.

('Writing' is not equal to 'time', so we add this 'how' phrase in the middle.  There is no grammar problem with the end of this sentence, but I am not sure what it means.)

I extremely scared of this situation, therefore I read as many books as I can these days to keep my enthusiasm for writing, open my mind, and practice my study skills, which are enormously important to me.

(more: 更多, many: 许多; the word 'enthusiasm' is usually used with the preposition 'for', and 'cogitation' is a very rare technical word from psychology, 'to open (one's) mind' is a common way to express this idea.)

In addition, I found a serious problem: that I spend a lot of time on my makeup.

('Making up' has so many different meanings, this sentence was not clear   I guessed that your meaning was 妆化.)

faced with this situation , I really don't know how to deal with it .

(The phrase 'faced with' fits better if there is an action verb after the comma.  Your sentence us fine and clear, but a simpler way would be to say 'I really don't know how to deal with this situation.')

I hope I can improve my efficiency in all aspects to adjust to college life better !