* Noun: This is the most common usage. It refers to a state of difficulty or distress.
* Example: "I'm having trouble understanding this math problem."
* Verb: Less common, but used to mean "to cause worry or discomfort."
* Example: "Don't trouble yourself with that, I'll take care of it."
* Adjective: Less common, but sometimes used to describe something as difficult or troublesome.
* Example: "This is a trouble spot on the road."
The context of the sentence will determine the correct part of speech for "trouble."