Avoid 『we』, because it is often unclear who 『we』 refers to. You and your marker? You and a co-author? The whole world???
It is also very bad style to refer to yourself as 『we』—writers sometimes do it when they have problems with their essay and they want to 『distance; themselves from it, saying in effect, 『Do not blame me for this result』.
Avoid 『we must teach like this』 or 『we should concluded that…』. If you do this, you are making two mistakes. First, you are telling your marker what to think and do (not a good idea) and second, you are limiting your own position. You are saying 『things are defined and clear cut』, whereas they are often NOT!
You
Avoid 『you』. It is too personal and conversational. That the 『expert talking to learner』 style used in textbooks and handbooks is NOT appropriate in formal writing, since you are still a learner.
I
You can use 『I』 at several points, but making certain the sentence refers to something you are, as a student and as the author of the assignment, responsible for. Thus you could put 『I shall divide the argument into two main sections』 (you could also write 『the argument is divided into two main sections』). On the other hand, you do not want to write, 『I have argued elsewhere that adults learn grammar faster than children』, as this makes you sound like a world expert with 30 books published!
Try and avoid 『I think X is a good idea』. We want you to argue the case WHY X is or is not appropriate, rather than simply assert(=state) that you think it is. This is one of the big differences between conversation and university assignments. In an assignment, you have to make sure you give the evidence for opinions and you need to use impersonal verbs like 『seem』.
Thus you would write, 『Smith would seem to be wrong in arguing that…』 or 『This seems incorrect』, rather than 『I think Smith is wrong』.
有時候，主語I,We後面常常緊跟動詞，這樣的情況下，可以用[形式主語it] 來改寫句子，例如I think，I believe，I feel，I argue，I agree 等等。都可以這樣換：I argue that prices should be higher.可以改寫成It is argued that prices should be higher.這樣在本質上，[形式主語it]都是對原來句子的一種改寫，這在學術論文裏是非常常見的，常用的大概是以下：It should be argued that…，It has been suggested that…..，It can be seen that….，It appears that…..，It was said that….，It is generally agreed that….，It was found that….，It could be concluded that…，It is doubtful that，It tends to be…，It seems that….，It is widely accepted that…。
2. 更換主語，也就是多使用被動語態。
由於是中文的思維慣性，在我們寫論文的時候，都是順著慣性大量使用有靈主語（I，We，you，me）等。在我們的漢語裏，主語一般都是有靈的，再說的俗一點就是有生命的，它們往往都是句子中陳述的對象，指明說的是「什麼人「或是」什麼事「。中文的習慣是以人做主語，動作的發出者一般是人。而英文，有一種實踐，是以物、或者抽象名詞做主語。一般認為這是學術、正式寫作的慣例，但也有一個很有力的趨勢是要求寫作更為人性化，有人味。一般認為這是學術、正式寫作的慣例，但也有一個很有力的趨勢是要求寫作更為人性化，有人味。例如，描述一個實驗。中文的習慣，是我們怎麼怎麼設計，（我們）採用了什麼什麼方法，（我們）得到了什麼什麼結果。這裡就有很多人（人稱代詞）。（PS，發表文章裏，少有單一作者，所以 We 出現得遠比 I 多，顯得特別團隊，特別有氣勢。I 就感覺上是一個人在胡搞瞎搞，特別弱。）按照去掉人的英文實踐，就是：實驗的設計是什麼什麼樣的。按照去掉人的英文實踐，就是：實驗的設計是什麼什麼樣的。這裡的主語，或者是具體的物體，或者是抽象的行為和概念。人，都是隱藏在後面的。顯得就客觀多了。在大家寫作的時候，應該有意識的扭轉慣性，主動更換主語。
