A. The word modify in grammar is a technical term. It doesn’t mean the same thing as modify in nontechnical usage. Also, importantly, it doesn’t mean the same thing as the semantic word describe.
When X modifies Y in grammar, Y is the head of a phrase and X is a modifier inside that same phrase. Look at these two clauses:
But if there’s a more attractive alternative, a mosquito may move on to that someone or something instead.
But if an alternative is more attractive, a mosquito may move on to that someone or something instead.
1. Look at the adjective phrase more attractive. In one clause, that phrase is inside a noun phrase. Is it in the first clause or the second clause?
2. Give that noun phrase:
3. Is the adjective phrase before or after the head noun?
4. Based on your answer to 3, is the adjective phrase attributive or postpositive?
5. In the other clause, the adjective phrase is neither attributive nor postpositive, because it’s not modifying a noun. Instead, it’s a predicate complement. What verb is licensing the predicative complement in that clause?
6. That adjective phrase is predicative.
Now examine this clause carefully:
These food sources are more attractive alternatives.
Is the adjective phrase there attributive or predicative? Why?
Now dó the following exercise. For each of the following adjectives, decide whether it can be used in attributive function, whether it can be used in predicative function, and whether it can be used in postpositive function. Give a correct or an incorrect clause as evidence for each answer. Thus, for each item, you should have three clauses.
An attributive adjective comes inside a noun phrase, before the head noun – example:
When the hero or heroine enters the realm of Baba Yaga, he or she faces not only the unknown territory of death but also the possibility of attaining his or her goal.
A postpositive adjective comes inside a noun phrase, after the head noun – example:
For reasons unknown, he put her on edge.
A predicative adjective is the head of a predicate complement, so it has to be licensed by a verb that licenses PCs – example:
The state of the vineyard is unknown.
It’s very rare that an adjective can occur in all three positions. You’re going to find a lot of cases where one or two positions causes ungrammaticality.