"as"后面加动词时，通常使用 动词的ing形式。这种结构可以表示伴随情况、原因、时间等。以下是一些具体的用法示例：
作为伴随状语
She used her family's history as a base for her novel.
He sat in the armchair, reading a newspaper.
表示原因
As it was getting late, we decided to go to bed.
表示时间
As soon as he arrived, the meeting began.
表示方式或程度
She sings as beautifully as her sister.
表示比较
This film is as interesting as that one.
总的来说，"as"后面加动词ing形式是一种常见的语法结构，用于表达各种伴随情况或状态。希望这些示例能帮助你更好地理解这种用法。