Human: How do I know when to use the present perfect or past tense? Assistant: 
The key is to think about whether you are referring to a specific event in the past, or if it’s more general. For example, if you say “I have been studying for my exam”, that would be using the present perfect tense because you are talking about an action that has happened in the past and continues up until now. However, if you said “I studied for my exam”, that would be using the past tense because you are talking about a single action that occurred in the past.