动词加ing形式是把动词改成了动名词比如swim --swimming。
I like to swim.这里swim乃动词。
I like swimmin。这里swimming偏名次属性。
因为英语中，一句话 一般允许一个谓语（动词充当），但一句话不止一个动词，一旦前面一个动词做了谓语 其他动词只好做非谓语（即to do /doing/done)。
例如：JIM喊我去打球这里有2个动词喊和打。
英文翻译为JIM asks me to play ball (ask做谓语play就只好做非谓语就变成to ask了)。
1、正在进行时中,谓语动词后加ing。如:I'm playing football。
2.当动词做主语时，要用动名词，即动词加ing。如：Making salad。
3.--些特殊表达.动词后再用动词要用动名词.如:enjoydoingsth。
practice doing sth. mind doing sth. finish doing sth. keep doing sth。等
4、当一个句子已经有一个动词了。
5、一些固定的词和词组后面比如。
feel like doing、risk doing、it is no use doing。
列举一些常见的后面加doing的: keep enjoy excuse practice mind
avoid、appreciate risk consider can't help give up imagine finish、think of suggest hear of be fond of、insist on、aim at。其实就是大多数介词后面
6、表示主动。
7、表示进行。
动词ing形式变化规则：
1、–ing分词的构成主动形式 被动形式 doing being done 一般式 完成式 having done having been done 否定式：
not+--ing/not having(been) done 不是 having not (been) done。
2.一般式和完成式的用法--ing分词的一般式表示和谓语动词所表示的动作同时进行的一个动作；完成式表示先于谓语动词动作之前的一个动作。
如： Walking along the street, he caught sight of an old friend of his. Not having studied his lessons very hard, he failed the examinations.
3.---ing分词的被动式当－ing分词与它的逻辑主语构成被动关系时，需要用被动形式。根据－ing 分词动作发生的时间，－ing分词的被动式分为一般被动式(being done)和完成被动式(having been done),如：
The question being discussed is very important. Having been praised by the teacher, he works even harder.
4.---ing分词的句法功能：
1)---ing分词作主语 Learning English has become a part of his life. It is no use trying to repair the ship. These holes are much too big.
2) ---ing分词作宾语 以下动词必须跟---ing分词作宾语：admit/ appreciate/avoid/consider/delay/deny/dislike/enjoy /excuse/finish/image。
keep/mind/ miss/postpone/put off/practise/risk/stand/ stop/ suggest / give up/cannot help。
食戟之喵
