Establish a time frame of reference and use it consistently throughout a sentence, paragraph, or essay. For example, if you decide to summarize a story in the simple present tense, take care not to slip into the simple past.
Use the basic time frame to make choices of tenses to show actions that occur earlier or later. For example, if you are summarizing a story in the simple present tense, you can report an earlier action in the present perfect:
When she arrives at the secret room, the heroine realizes that she has forgotten the key.
If you were summarizing the story in the simple past tense, the past perfect would work for the earlier action:
When she arrived at the secret room, the heroine realized that she had forgotten the key.
Do not shift tenses for no reason.
Most people know that cigarettes are bad for them.
Ben returned home after he had worked for six months in Chicago.
Most people know that cigarettes were bad for them.
Ben returned home after he has worked for six months in Chicago.
Click the correct sentence.