If you pay enough attention when you study in Mandarin language courses in China, you may find that many Chinese people often say并非 like我并非是那种什么都能泰然处之的人. In this case, you should know it is an adverb meaning not and it is often used to negate certain opinions or ideas for the purpose of real conditions. It often carries the tone of refuting. The most frequently seen form is 并非如此. For example, you can say报上说那里的经济情况已经开始好转，可是事实并非如此.

The word 偶然is also often used in daily conversations such as 警方认定这是一起偶然事故. 偶然functions as an adjective to indicate that the things shouldn’t happen but happened or things do not follow certain principles. You can say 这个路段发生交通事故并非偶然，这里的转弯设计得有问题.

The third one you should understand is about willing to do something. When seeing the word 懒得, the foreign students who study Mandarin online may think it is the meaning of being lazy. But precisely, it is a verb implies somebody is not willing to do something. It is often followed by verbs and verb phrases as object. Accordingly, you can make sentence like 宿舍有厨房，但是他们都懒得做饭.

For some of the overseas learners who come to learn Chinese language in China, the pattern …, 而…则… may be a little difficult to understand. As a matter of fact, it is used into a sentence with two clauses to show the comparative meaning between them. In this pattern, 而…则… leads to the conditions that are opposite to the one mentioned in the former part. For example, 老王工作能力很强，同样的工作，我紧紧张张地干了一上午， 而老王则只用一个小时就轻松完成了. It is often used in formal written language.