-ing 结尾英文单词词性1)ever being able to 中的being2)finish reading th

He was in despair of ever being able to pay off his debts.
这是一个介宾结构,介词OF +名词,所以本来是情态动词BE ABLE TO ,BE 要变成名词形式BEING After finish reading the book, you can consider the difficult ones.
这句中的READING 是一个现在进行时态,FINISH DOING STH,是说做完正在做的事,本来应为FINISH WHAT IS READING ,省略了WHAT IS .变为现在分词.
We all stand by helplessly, waiting to die.
这一句是分词结构,WAITING现在分词做伴随状语.这么讲,你能明白吗?

三个都是动词加-ing，但是前两个应该是动名词做宾语，第三个是动词进行式做补语。

信息不全，最高给出全句。He was in despair of ever being able to pay off his debts. After finish reading the book, you can consider the difficult ones. We all stand by helplessly, waiting to die. 我想问的是， 这些词具...

由于第一句话中有个介词短语，介词of后面跟名词或者动名词，所以动词be必须用v-ing形式，即being词性为“动名词”；第二句话，finish doing sth是个固定句型，意为完成做某事，reading是read的现在分词形式，也可以说它是动名词；第三句，主语是we，stand和wait做并列谓语，wait前省略了主语we所以必须用动名词形式。补充一下，其实动名词v-ing和动词的现在分词形...