For example, the tense may change between the methods section and the discussion section. The abstract is usually in the past tense due to it showing what has already been studied. Example: “This ...

The past tense is used for things that have already happened. He was sticky. The present tense is used when something is happening now or when something happens regularly. He is sticky.

I walked to the shop. However, not all past tenses are written like this as there are exceptions which need to be learned separately. For example: I bent down to pick up a penny. The correct past ...