Question

six years old six-year-old 两者区别是什么

Answer 1

six years old是短语，在句子中做表语,放连系动词后，比如：
He is six years old.
six-year-old是复合形容词，结构为数词+名词＋形容词，在句子中作定语，放名词前,相当于形容词,比如：
He is a six-year-old boy.

拓展：
复合形容词的类型：
(1)名词+过去分词 man-made satellite 人造卫星
(2)形容词+现在分词 a good-looking man
(3)形容词+名词 second-hand cars
(4)数词+名词-ed three-legged chairs三条腿的椅子
(5)数词+名词 400- metre race
(6)副词+现在分词 hard-working students
(7)副词+过去分词 well-known writers
(8)形容词+形容词 a dark-red jacket
(9)形容词+过去分词 ready-made clothes 成品服装

含有形容词的常用句型：
(1) It’s+adj. of sb. to do sth.
(good/ kind/nice/polite/clever/foolish… )
It’s very kind of you to help me.
(2) It’s +adj. for sb. to do sth.
(difficult/easy/hard/dangerous/usefulinteresting/important…)
It’s important for us to learn English well.
(3)下列形容词后常跟动词不定式
表示情感或情绪的形容词：glad,pleased,sorry,sad,afraid,thankful…
I'm glad to see you.
表示能力，意志或推测的形容词：ready,able,sure,certain…
I’m sorry to hear that.

某些现在分词和过去分词可作形容词，例如：
the moving story 令人感动的故事
a moved boy 一个被感动的男孩
a frightened child 一个被吓到的孩子
a frightening film 一个恐怖电影