Tomthinks playingbasketball .
中的palying basketball 是動名詞作定語因為是定語所以加ing

動詞的-ing形式是動詞的一種非謂語形式,由動詞原形加-ing構(gòu)成,包括-ing分詞和-ing動名詞.可以在句子中用作主語、表語、賓語、賓語補語、狀語和定語.
一、作主語
1．一般形式
Seeing is believing.
眼見為信.
Coming to Hangzhou by train tkes about 16 hours.
乘火車到杭州要16個小時.
2．通常為了避免句子主語過于冗長,用it作形式主語.如：
It’s nice talking with you.
和你談話很高興.
It’s no use arguing with him.
跟他爭論沒用.
3. “There + be + no + -ing”結(jié)構(gòu),此結(jié)構(gòu)的意義相當(dāng)于“It’s impossible + 不定式”. 如：
There is no harm in doing so.
這樣做沒有害處.
二、作表語
動詞-ing可用來作表語.如：
This food smells inviting.
這種食物香味怡人.
My favorite sport is swimming.
我最喜歡的運動是游泳.
Their job is cleaning the window.
他們的工作是打掃窗子.
三、作賓語
1．動詞-ing形式可以用作動詞、短語動詞和介詞的賓語
I warned her against driving fast.
Jim dislikes eating chocolate.
2．有些動詞和動詞短語后接賓語的非限定性動詞時只能是-ing分詞,常見的這類動詞有：admit, acknowledge, advise, appreciate, avoid, delay, deny, dislike, enjoy, excuse, escape, fancy, finish, forgive, face, endure, involve, give up, imagine, mention, mind, miss, pardon, practise, require, resent, resist, suggest, recall, resist, understand等.
The doctor advised taking more exercise.
醫(yī)生建議多鍛煉.
I suggest doing it in a different way.
我建議用不同的方法做.
3.大部分“動詞+介詞“短詞動詞,只能后接動詞-ing作賓語.這些動詞短語有：think of, give up, aim at, put off, insist on, persist in, be good at, do well in, can’t help, keep on, leave off, feel like, be tired (afraid, capable, fond) of, set about等.
以下為to作介詞的短語有：be used to, object to, devote oneself to, stick to, respond to, look forward to, see to, submit to, adapt to, apply to, accede to, get to, prefer to, adjust to, owe to, react to等.
Do you feel like having a drink?
你想喝點飲料嗎?
I prefer swimming to playing basketball.
我喜歡游泳勝于打籃球.
4．有些動詞既可能帶-ing分詞作賓語,也可以帶to不定式作賓語,但在語義上卻有很大的差別.如：
（1）chance to do 碰巧去做某事
chance doing 冒險試一試做某事
（2）forget to do 忘記要去做某事
forget doing 忘記曾做過某事
（3）go on to do 接著又做另一件事
go on doing 繼續(xù)做同一件事
（4）remember to do 記得要去做某事
remember doing 記得曾做過某事
（5）stop to do 停下來去做某事
stop doing 停止做某事
（6）try to do 努力做某事
try doing 試一試做某事
（7）regret to do 對將要做的事表示遺憾
regret doing 對做過的事表示遺憾
（8）mean to do 打算/想做某事
mean doing 意味著/意思是做某事
四、作賓語補語
I found the parade quite interesting to watch.
這種用法通常用在下列幾類動詞中,后接賓語然后加上-ing 分詞,構(gòu)成復(fù)合賓語結(jié)構(gòu),-ing分詞充當(dāng)賓補成分.
1．表示感覺和心理狀態(tài)的動詞,如：see, hear, feel, find, smell, watch, find, listen to, look at, notice, observe等.如：
There we found him watching TV.
我們發(fā)現(xiàn)他在那兒看電視.
I heard someone knocking at the door.
我聽見有人在敲門.
2.在有些動詞（如：regard, describe, accept, think of, quote等）之后,可由as引出-ing分詞詞組作賓補.如：
They regarded the contract as being invalid.
他們認(rèn)為合同無效.
They described the child as being very clever.
他們描述這孩子非常聰明.
3.使役動詞,如：set, keep, have, get, leave, catch等.如：
Can you get my watch going again?
你能使我的表再走起來嗎?
This sets me thinking.
這使我思考.
五、作狀語
-ing分詞作狀語表示在進行一動作的同時所進行的另一動作,它對謂語動詞起修飾和陪襯的作用.分詞作狀語可以表示時間、原因、條件、讓步、結(jié)果、方式或伴隨情況.
Having cleaned the rooms we began to weed the garden. (時間)
打掃完房間,我們開始在花園里除草.
Coming into the room, she saw everybody already at their work. (時間)
進屋以后,她看到人人都在工作.
Being ill, he couldn’t go to school. (原因)
因為生病,他不能去上學(xué).
Having no interest in the topic, he didn’t go to the lecture. (原因)
由于對這個話題沒有興趣,他沒去參加講座.
Working diligently, you will certainly succeed. (條件)
只要刻苦學(xué)習(xí),你會成功的.
Using atomic energy, we can build spaceships. (條件)
利用原子能,我們能夠建造太空船.
Granting the achievements to be great, there is still something to bi desired. (讓步)
(盡管)成績是巨大的,（但）仍有一些要求改進的東西.
My car was caught in a traffic jam, thus causing the delay. (結(jié)果)
我的車被交通擁擠堵住,所以延誤了.
Traveling by train, we visited a number of cities. (方式)
我們坐火車訪問了好多城市.
Mary sat by the window of the classroom, reading a book. ( 伴隨)
瑪麗坐在教室的窗戶旁,正在讀一本書.
六、作定語
分詞作定語時和形容詞的功能是相似的.-ing分詞可以單獨作定語,如：
a smiling face 笑臉
a leading figure 領(lǐng)導(dǎo)人物
-ing分詞還能構(gòu)成合成詞作定語,如：
easy-going man 好說話的人
當(dāng)分詞短語做后置定語時,可以轉(zhuǎn)換成定語從句.
She went on board the train leaving for Shanghai.
=She went on board the train, which was leaving for Shanghai.
她乘坐了去上海的火車.
There are two roads before us, one leading to the beach, the other to the park.
=There are two roads before us, one which leads to the beach, the other to the park.
在我們面前有兩條路,一條通向沙灘,另一條通向公園.