The main exception to consistent usage in tense is the third person singular in the present tense. The pronouns he, she, and it, as well as the nouns they represent, get a verb ending in s only in the present tense. Examples:
I write reports, you write proposals, and Bill (or he) writes procedures.
We describe objects, they describe events, and the report (or it) describes the protocol.
I have a car, you have a boat, and Yvette (or she) has a plane.
Notice in the past and future tense how the verb forms are consistent:
I wrote the article, you wrote the chapter, and Jill (or she) wrote the book.
We will read the analysis, they will read the report, and Paul (or he) will read the claim.
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