I have just done some research, and I am now prepared to give an opinion regarding the question: "What does the adverb 'well' modify?" Answer: It modifies the prepositional phrase ("below the usual standard"). Here are some examples that I found (the adverb is in capital letters): 1. He arrived EXACTLY (on time). 2. She was standing ALMOST (at the top). 3. The plane is JUST (below the horizon). P,S. There are some people who believe that the adverb modifies only the preposition, such as "on," "at," and "below." I believe, however, that most people feel that it modifies the whole prepositional phrase. Therefore: The meal was WELL (below the usual standard).

"Well below" means "very much below". "To a high degree", if that makes sense to you. This is sometimes used when talking about the weather. Example: "The temperature today is well below the freezing point." Some other ways to phrase it are, "The meal was much worse than it usually is." Or, "The meal was not at all up to the usual standard of quality."

"well below the usual standard" is a phrasal adjective, that is, the whole phrase functions as an adjective; it modifies the noun (the meal). It's easy to understand if you think about: "the meal was (good)","the meal was (well above the usual standard)"; "the meal was (bad)", "the meal was (well below the usual standard)". I hope this helps

"The meal was well below the usual standard." 1. If we omit "well," we get "The meal was below the usual standard." a. The meal = subject. b. was = linking verb. c, below the usual standard = a prepositional phrase acting as an adjective. It means something like "substandard." ("below" = preposition) 2, "Well" is an adverb in your sentence. It cannot be an adjective, for the meal was NOT "well." In your sentence, "well" means "to a great extent." a. The question is: what does the adverb "well" modify? i. I am not sure, so I shall not answer. I do not want to give you any wrong information.