1. 用法：相当于形容词的用法，用来修饰名词；
2. 分类：前置定语和后置定语；
3. 条件：单个的单词通常作前置定语，放在名词之前；多个单词或是短语通常作后置定语，放在名词之后；
4. 单个的动词-ing形式作前置定语的用法：
(1)表示主动：动词-ing形式和它所修饰的名词为主动关系；
(2)说明被修饰名词的用途和性能；
e.g. a reading room＝a room which is used for reading阅览室
running shoes＝shoes for running跑鞋
a working method＝a method for working工作方法
(3)表示所修饰的人或物的动作或状态，在意思上接近一个定语从句，可以表示正在进行的动作，也可表示经常性动作或当时的状态；
e.g. developing countries＝countries that are developing
an ordinary-looking house＝a house that looks ordinary
a puzzling problem＝a problem that puzzles somebody
(4)表示所修饰物的特征、性质和状态(动词ing形式相当于一个形容词)，常译作“令人……的”。
①常用来作定语的现在分词有astonishing(令人惊奇的)，amusing(使人发笑的)，confusing(令人困惑的)，disappointing(令人失望的)，boring(令人感到无聊的)，encouraging(鼓舞人心的)，inspiring(鼓舞人心的)，moving(令人感动的)，tiring(令人感到疲惫的)，interesting(令人感到有趣的)，surprising(令人感到惊讶的)等；
②注意；此类定语通常用来修饰指物的名词。
e.g. This is an interesting book and many students like reading it.
That is a tiring thing and I just don’t want to talk about it.
5.动词-ing形式作后置定语：
(1)作定语的动词ing形式如果是一个短语，则应放在被修饰词的后面，作后置定语，表主动关系，可转换为相对应的定语从句；
e.g. They lived in a house facing the south.
= They lived in a house which faced the south.
Do you know the boy playing basketball?
= Do you know the boy who is playing basketball?
(2)分类：后置定语和所修饰的名词之间没有打“,”的，可以转换为限制性定语从句；后置定语和所修饰的名词之间打了“,”的，可以转换为非限制性定语从句。
e.g. Tom is the person helping my mother yesterday.
= Tom is the person who helped my mother yesterday.
I like the apple, tasting sweet.
= I like the apple, which tastes sweet.
6.专题练习
(1) I know you’re dying to hear all about my life here，so I’ve included some photos_____ (help) you picture the places I talk about.
(2) The boys_________ (come) across anything like this before started jumping out of the windows.
(3) Is he the man _________ (want)to see you？
(4) I don’t like people always_____ (think) of themselves.
(5) The sun heats the earth，______(make) it possible for plants to grow.
(6) Many westerners _________ (come) to China cook much less than in their own countries once they realize how cheap it can be to eat out.
答案见于公众号初高中英语学习资料