The most common way to use "dusk" in a sentence is as a noun signifying the time of day between daylight and night. An example is, "She loves to sit on her porch at dusk and enjoy the quiet cool that overtakes the neighborhood."
Another meaning of "dusk" is "partial darkness or gloom," as in the sentence, "After they heard the bad news, a kind of dusk settled over the house."
Poetic uses of "dusk" include as an adjective meaning "tending to darkness" and as a verb meaning "to become dark." A sentence using "dusk" as an adjective is, "The skirt is such a dusk blue shade that it almost appears black." An example of using "dusk" as a verb is, "As the storm approached, the sky began to dusk threateningly."