Grammatically speaking, Chinese language is a relatively simple language for it does not have verb conjugations. The same form of verbs can be used for all tenses. For example, ta1 lai2 wo3 jia1 他来我家 can be referred to something happened already as past tense, as he came to my house, or it can mean something will happen in the future, such as in this dialogue: A: ni3 yao4 qu4 ta1 jia1, hai2 shi4 ta1 lai2 ni3 jia1 你要去他家，还是他来你家？You want to go to his house or he will come to your house? B. ta1 lai2 wo3 jia1 他来我家 he （will） come to my house.
Chinese negatives are also quite easily formed by using those following negation words:
不 bu4， 没有 mei2 you3， 别 bie2：
不 bu4
不bu4 is used before a verb to form the negative in the present or the future. But remember, bu4 will never use with you3 (有 have); never say bu4 you3 不有。If you want to negate you3 (have 有）， you must use mei2 没。
Wo3 bu4 chi1 我不吃 can be “I don’t want to eat now” or “I won’t eat; I am not going to eat”
Ta1 bu3 xie3 他不写 can be ” He doesn’t write” or “He is not going to write”
Usually bu4 is pronounced as the fourth tone, however, when bu4 is put with a verb that is also the fourth tone, the bu4 will be changed to bu2, the second tone. For example: bu2 kan4 不看 don’t look, bu2 yao4 不要 don’t want.
没有 mei2 you3
没有 mei2 you3 is used before verbs to form the negative in the past: 我没有吃饭wo3 mei2 you3 chi1 fan4 “I haven’t eaten”. Mei2 you3 can be shortened as mei2, so the above sentence can be: 我没吃饭 wo3 mei2 chi1 fan4.
Literally, 没有 mei2 you3 mean “not have” (我没有钱 wo3 mei2 you3 qian2, “I don’t have money”). In this sense, mei2 you3 + noun can be used for all the tenses. For example, you can say: 昨天我没有钱 （zuo2 tian1 wo3 mei2 you3 qian2， I did not have money yesterday), 今天我也没有钱 （jin1 tian1 wo3 ye3 mei2 you3 qian2， today, I still don’t have money), 明天我还是没有钱 （ming2 tian1 wo3 hai2 shi4 mei2 you3 qian2， tomorrow I still won’t have money).
别 bie2
别 bie2 means “don’t” when it got placed before a verb. For example 别开玩笑 bie2 kai1 wan2 xiao4 “don’t joke about it”. In order to soften the command a bit, you can add a particle 了 le5 on the end or use qing3 请 at the beginning, or use both to soften the tone and makes the request more polite. 请别开玩笑了。