不加，只有动词和个别形容词有ing形式，如:interesting,exciting动词-ing形式有两种词性，即动名词和现在分词。

遇到动词-ing形式时，需要根据“语法环境”判断它是动名词还是现在分词。如果是动名词，它实际上是一种名词形式，修饰语应该是形容词，而不是副词，如：Laying eggs is the ant queen''s full-time job. 产卵是蚁后的专职工作。Saying is easier than doing. 说比做容易Being a student, he was interested in books. 作为一个学生，他对书本很感兴趣。Not having studied his lessons very hard, he failed the examinations. 因为没有努力学习功课，他考试不及格。在need, want, require, be worth等动词(短语)后，作宾语的-ing分词常用主动形式来表示被动含义。如：Your shoes need cleaning. = Your shoes need to be cleaned. 你的鞋需要清洗一下了。This book is well worth reading. 这本书很值得一看。

不可以，只有动词才有ing形式。

副词后无需动词加ing, 但副词可以修饰以ing结尾的现在分词，如greatly suprising.