Present perfect or past perfect.
The two have worked together to write a book.
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Present Perfect
past perfect
To determine whether to use the present perfect or past perfect tense in the given sentence, let's first understand the difference between the two:
1. Present Perfect: This tense is used to describe an action that started in the past and is still ongoing or relevant in the present. It is formed by using the auxiliary verb "have" or "has" followed by the past participle of the main verb.
2. Past Perfect: This tense is used to describe an action that happened before another action in the past. It emphasizes that the first action was completed before the second action took place. It is formed by using the auxiliary verb "had" followed by the past participle of the main verb.
Now, let's analyze the given sentence: "The two have worked together to write a book."
In this sentence, we are talking about a completed action of the two individuals working together to write a book. It does not mention any specific time or event in the past that the action was completed before. Therefore, the present perfect tense ("have worked") is appropriate in this case.
If we were to use the past perfect tense instead, it would imply that their collaboration had already been completed before some other action in the past. However, without any context suggesting a specific sequence of events, the present perfect tense is the better choice.
Therefore, the correct tense in this sentence is the present perfect: "The two have worked together to write a book."