There are variations in the way verbs form the past tense. They can be looked at in the following way: ...

Use the preterite ... Most Spanish verbs are regular in the preterite tense. The Spanish preterite tense is used to describe completed actions in the past. For example: Fui al cine ayer.

Normally in the past tense, you do not need to worry about subject-verb agreement because you can conjugate most regular past tense verbs to the singular or plural by adding an -ed to the end of the ...

In the methods section one would use past tense due to what they have done was in the past. It has been debated whether one should use active or passive voice. The scientific journal Nature states ...