How do you use the word SULLENLY in a sentence?

Answer 1

Well, "sullenly" is a synonym to "angrily," "grimly" or "morosely," so the word fits perfectly in an aggressive or hateful sentence.

For example: "Angela sullenly gripped Henry's armed and forced him around the corner, making a horrid bruise."
That was not a very aggresive nor hateful sentence, but it expresses anger. Though not aggresively, it is definitely a good sentence for the word.

"Ginger gawked sullenly at the dim-witted, out of proportion face that had made her feel nothing but pain for the past nine years and quickly jumped off her feet to engage Peter with the same pain in just a small moment."
This one's aggressive and hateful. Ginger hates Peter, and feels the urge to hurt him.
Although the first example wasn't aggresive or hateful, it expresses a deep feeling, and is by far a better sentence than the second example.
Expressing feelings is very important when trying to make sentences if you want to make sure the reader gets into it.
If the sentence is merely for an assignment, the second example is better due to the fact that "sullenly" is used best as an example in an aggressive and hateful sentence.

Answer 2

I would not sully her reputation with that piece of gossip.