Markers of English tenses

There are 16 tenses. Tenses can be divided into four types according to time: past tense, present tense, future tense and past future tense; According to the action, it can also be divided into simple tense, progressive tense, perfect tense and perfect progressive tense. So it can be combined into *** 16 type, which can be used according to the specific language environment (taking the first person as an example): 1. Simple past tense (I did it); General present tense (I will); I will do it; I'll do it). 2. I'm doing it; I am doing it; I will do it; I will do it). 3. I did it; I did; I will do it; I have already done it). 4. I have been doing it; I have been doing it; I will keep doing it; I will keep doing it). In the past and in the future.