Can I have an example of a sentence using conjunctive adverbs (comma rule) and another sentence with an example of commas with descriptive adjectives.

Conjunctive adverbs connect one clause to another clause, or one idea to another idea:

Joanne was very good at math; however, she is not good at English.

Descriptive adjectives can be separated with commas in a sentence such as:

Joanne did not want to pet the smelly, wet dog.