Present: Melvin seems happy today.
Past: Melvin looked depressed yesterday.
Future: Melvin will look different after his surgery. (Note that the future tense has a helping verb/modal auxiliary, usually will.)
The simple present and past tenses don't use a helping verb. The simple present tense means actions occurring now or habitually. The simple past means actions completed at a specific time in the past.
To write well, I need to understand tenses.
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