A modifier does exactly what it sounds like: it changes, alters, limits, or adds more info to something else in the sentence. A modifier is considered dangling when the sentence isn't clear about what is being modified. For example, "The big" doesn't make sense without telling what is big which leaves "big" as a dangling modifier; but, "the big dog" is a complete phrase.
Since a modifier has to more information about something, by definition that means the something it is modifying or limiting has to exist. That means, of course, that you can't just say The happy. If you did, people would immediately ask you: "the happy what?" That missing what is the thing being modified.
It seems pretty obvious and intuitive when written in a simple sentence, and it seems hard to imagine a situation in which a modifier would be left dangling. However, modifiers don't always have to be simple words or phrases like happy, and sentences aren't always simple.
Phrases can also act as modifiers, providing additional information about something else in the sentence. When this occurs, and when sentences become more complex, dangling modifiers can sometimes exist and get lost in the complexity of the language.
Problem: This is a dangling modifier because we do not know who or what was hoping to garner favor. It is unlikely that the parents were hoping to garner favor, since they wouldn't have given an unimpressive gift to themselves.
Correction: This sentence could be corrected by adding a proper subject, or identifying the person who was hoping to win over the parents. For example,
Hoping to garner favor, my new boyfriend brought my parents a gift that sadly unimpressed them.
Now, the modifier is no longer dangling, since the subject- or the person- who is hoping to garner favor is identified.
Problem: Here, it seems as though we have a subject- my. However, my is part of the modifier and not the subject itself.Correction: We need a subject that is modified by hoping to excuse my lateness, since obviously the note didn't have those hopes.
Hoping to excuse my lateness, I wrote a note and gave it to my teacher.
Now, the problem is resolved. I am the person who is hoping to excuse my lateness, so I wrote a note and gave it to my teacher. My note may not get me out of trouble, but at least I won't also have bad grammar!
Problem: Again, we are left wondering exactly who read the great new book. The phrase can't possibly be modifying the movie, since the movie can't read.Correction: A subject must be added so the modifier has something to describe, change or limit.
After reading the great new book, Anna thought the movie based on it was sure to be exciting.
Now that you've seen some examples of dangling modifiers, it should be pretty easy to see how often this problem can crop up unnoticed. The best way to avoid this grammatical error is to ask yourself exactly what is being described or modified by the phrase or word. If you don't have an answer, you may be facing a modifier that is dangling.
A modifier modifies or provides more information. In grammar, adverbs and adjectives are both modifiers. Adverbs modify verbs, adjectives and other adverbs. For example:
Happy is an adjective modifying the noun boy. Very is an adverb modifying the adjective happy
Very is an adverb modifying quickly. Quickly is an adverb modifying the verb ran
Modifiers must be as close as possible to the thing they are modifying. Otherwise, confusion can result. For example, it wouldn't make a lot of sense to say "The very quickly boy ran", since very quickly are not modifying or describing boy.