being a good insulator,rubber is often used in cables
问题描述：
being a good insulator,rubber is often used in cables
为什么用being?
答
翻译如下：作为一种良好的绝缘体,橡胶经常被用在电缆上.
being a good insulator 是用来说明后面橡胶为什么被经常用在电缆上,是原因,所以用being