1, the abstract part, generally needs to use the simple past tense. As for concise explanation sentences, you can use the present perfect tense. But in order to emphasize the importance of research, such as explaining the current situation of the world or the specific field you are studying, you can also use the simple present tense.

In the introduction, you can mix the simple present tense and the simple past tense. The simple present tense is used to discuss eternal facts, and the simple past tense is used to describe early research findings, which can be your own or others'.

3. It is a bit tricky to use tenses in literature review, because you should not only consider the format requirements (APA, AMA, MLA and other formats), but also consider how you discuss the literature. The simple past tense is usually applied to: the researcher's name is the subject of the sentence, and then discuss the research methods or results.

4. The usage of partial tense in methodology is clear. Just choose between the past tense and the present tense.

Introduce what you have done in the simple past tense, and you may notice that the passive voice is often used when describing the operations of researchers. This method can put more emphasis on what was done rather than who did what. Although passive voice has become the mainstream in recent ten years, it is quite recommended to mix active voice and passive voice to improve the readability of the article.

5. Conclusion The usage rules and methodology of verb tenses are somewhat similar. Discuss the actual results in the simple past tense. Explain charts, tables and schematic diagrams in the simple present tense. And the sentence voice can't be mixed with active and passive.