定义：形容词是用来修饰名词的词，描述名词的性质、外观、特点等。功能：形容词可以做定语、表语或补助语。分类：主要分为两类：描绘性形容词和限定性形容词。
● 描绘性形容词主要用来描绘大、小、新旧、颜色、质量等。
● 限定性形容词主要用来限定所修饰词的数量、距离及范围所属等。1.当形容词修饰单数可数名词时，必须与冠词连用：
a lovely girl, the naughty boy2.形容词可与系动词连用，做表语，说明主语的性状。常用系动词有：be, become, seem, appear, feel, look, taste, smell, sound, remain, go, turn, keep, stay, etc.
The dish tastes delicious.
The music sounds sweet.
The milk went bad.
小心陷阱：feel，smell，taste，look，keep有时可以用作实义动词，并可以用副词修饰。
He looked me up and down carefully.
I tasted the soup slowly to see whether it was salty.3.形容词用作后置定语。(简单理解：一般的形容词修饰名词时放在名词前面，但有些形容词修饰名词时放在名词的后面)
a river navigable(一条可通航的河)
sight visible (可见的景象)
person responsible(负责人)注意：responsible person(有责任心的人)
the best way possible(尽可能好的办法)
the number necessary(必要的数量)
the people present(在场的人)4.只能作表语的形容词(1) 某些表示健康状况的形容词。
well(身体好的)，ill(病的)，faint(虚弱的)，poorly(身体不好的)
示例：His mother has been ill for a long time.
特别注意：sick是个特例。它既可做表语，又可做定语。
He is sick for a couple of days.(他病两三天了)
He is a sick person.(他是个病人。)(2) 某些以 a-开头的形容词。
如：afraid, alone, alive, asleep, awake, aware
The old man is alone in the house.(老人一个人在家。)
The teacher is alive with enthusiasm.(这位老师热情洋溢。)
He is asleep in his mother's arms.(他在母亲的怀抱中睡着了。)
I have been aware of the difficulty.(我已经意识到了困难。)
