Parallelism is achieving balance in sentences. When you present similar
points in a sentence, those points should have similar structure. This means
that if you have a list of adjectives, that each word you use in the list is
an adjective. If you are presenting a series of verbs, the verbs all use the
same form and tense. When sentences aren't parallel they are often very
awkward and difficult to read. Readers should not be distracted from the
meaning of your writing because your sentences aren't understandable.

Parallelism is achieved by finding the list within a sentence and then (来源：英语麦当劳－英语快餐EnglishCN.com)
checking to see what type of structure best suits your meaning. Sometimes a
preposition can introduce a list of three objects; at other times, each object
will need its own preposition. You make those decisions when you evaluate the
sentence you are trying to make parallel.

(来源：最老牌的英语学习网站 EnglishCN.com)

Chapter 8: Using Adjectives and Adverbs

(来源：英语交友 http://friends.englishcn.com)

Adjectives and adverbs are the words we use to describe. Adjectives describe
nouns and pronouns and adverbs describe verbs, adjectives, and other adverbs.
Without adjectives and adverbs we would not have the ability to distinguish
between similar items.

Adjectives generally appear before the word they describe. They can also appear
after a being verb like is, are, was, were, am, has been as well as other being
verbs like feels, looks, seems, smells, and sounds. When adjectives are used
with being verbs they will follow the verb rather than appearing before the noun
or pronoun. (来源：英语麦当劳－英语快餐EnglishCN.com)
Adverbs describe verbs, adjectives, and other adverbs. Adverbs answer
questions like How? How much? How often? When? Where? and Why? Adverbs can
appear either before or after the word they describe.

There are a few adjectives and adverbs that can be confused such as good and
well and bad and badly. Good and bad are adjectives; well and badly are adverbs.
It is also important not to confuse adjectives when you are making comparisons.
When you are comparing two items, you use the comparative form in which the
adjective ends with -er as in colder or has the word more in front of it as in
more intelligent. The superlative form compares three or more items and uses
either -est or the word most to create its form. Adjectives and adverbs are
often used in making comparisons because adjectives and adverbs are the tools we
use to distinguish one item from another

(来源：英语e问e答 http://ask.englishcn.com)

Chapter 9: Correcting Problems with Modifiers

(来源：EnglishCN英语博客基地)

Adjectives, adverbs, and prepositional phrases are all part of a group of
words, clauses, and phrases that are modifiers. Modifiers describe nouns,
pronouns, and verbs in a sentence. Modifiers help to make your writing vivid,
clear, and specific.

(来源：英语博客 http://space.englishcn.com)

The problems with modifiers are created when the modifier either has nothing
to describe in a sentence or it has been placed in the wrong spot in the
sentence so it describes the wrong element in the sentence. Misplaced or
dangling modifiers can create confusing and often unintentionally funny
sentences. (来源：英语麦当劳－英语杂志 EnglishCN.com)

The best way to avoid the problem of dangling or misplaced modifiers is to be