（动词的-ing形式作定语、表语和补语）
一、动词-ing形式作表语
1. 表示主语的内容 ,可以转换到句首作主语
Her job is keeping the lecture hall as clean as possible. (= keeping the lecture hall as clean as possible is her job) 她的工作是尽量使报告厅保持干净。
2. 表示主语具有的特征、性质和状态(动词ing 相当一个形容词）
The problem is quite puzzling. 这个问题很令困惑。
3.常用来作表语的现在分词有astonishing, amusing, confusing, disappointing, boring, encouraging, inspiring, moving, tiring, interesting, surprising等。
全析提示：动词-ing形式作表语时，其逻辑主语往往是句子中的主语，但用作表语的-ing形式也可带有自己的逻辑主语。What worries me most is her staying too late every night.(staying too late every night的逻辑主语是her)
二、 动词-ing形式作定语
1 单个的动词-ing形式可以作前置定语，一般具有两种含义。
① 说明被修饰名词的用途和性能。
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
② 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。
developing countries = countries that are developing发展中国家
an ordinary-looking house = a house that looks ordinary 看起来很普通的房子
a puzzling problem = a problem that puzzles somebody 困扰人的问题
2 作定语的动词-ing形式如是一个短语，则应放在被修饰词的后面,做后置定语，相当于一个定语从句。
They lived in a house facing south.(=which is facing south) 他们住在一所朝南的房子里。
Do you know the boy playing basket?（=Who is playing basket)你认识在打篮球的那个男孩吗？
The man visiting Japan (=the man who is visiting Japan ) is my uncle
正在访问日本的那个男人是我的叔叔。
三、动词-ing形式作宾补
1、动词-ing形式作宾语补足语常放在宾语后面，表示一个正在进行的主动性的动作，强调一个过程或一种状态。
When we returned, we found a stranger standing in front of the house.
2、当主句转换为被动结构时, 原来作宾语补足语的动词-ing形式便转换为主语补足语。
They found the film very exciting. = The film is found very exciting.
3、能用-ing形式作宾语补足语的几类动词:
1) 表示感觉和心理状态的感官动词，（常见的有see, hear, feel, smell, find, notice, observe, look at, listen to等）+ sb + doing sth（作宾补）I felt somebody standing behind me.
2) 表示指使意义的动词使役动词，（常见的有have, set, keep, get, catch, leave等）+sb/ sth + doing sth (作宾补）We kept the fire burning all night long.我们让火整夜燃烧着。
I won‘t have you running about in the room. 我不允许你在房间里跑来跑去。
4、see, hear, feel, watch等动词之后用-ing形式和动词不定式作宾语补足语的区别：
We heard the telephone ring. We heard the telephone ringing.
前者表示动作正在进行，后者表示（或强调）动作的全过程。