1、动词加ing前面必须加上be动词，形成be+动词ing（现在分词）作句子谓语，构成进行时态句子；2、动词作介词的宾语要加ing（动名词）；3、部分动词用动词做宾语。做宾语的动词要加ing（动名词）；4、一些固定句式后面要加动词ing（现在分词）；5、动词修饰名词做后置定语时，要加ing。
加ing例句
I Practising speaking English Every day.我每天练习说英语。
Could you mind opening the door?你介意开门吗？
I have finished reading three books.我已经看完三本书。
The old man Enjoys living in the country.这老人喜欢住在农村。
He is reading a book now.他正在看书。
He was watching TV when his mother came in.他妈妈进来时，他正在看电视。
