1．动词ing形式是动词的一种非谓语形式，包括现在分词和动名词两种。
动词ing形式在句中的语法作用：动名词在句中作主语、宾语、表语和定语，现在分词在句中作状语、宾语补足语和定语。
2．动词ing形式的时态和语态。
【观察例句】
Reading aloud is a good way to learn a language.
大声朗读是学习语言的一种好方法。
Having studied his lessons very hard, he passed the exam.
努力学习了功课, 他通过了考试。
The building being built now will be finished next month.
正在建设的建筑物下个月将完工。
Having been laughed at for his lameness, the boy became shy and inhibited.
那男孩因跛脚被人讥笑, 变得羞怯。
