a good insulator , rubber is often used in cables.A. Having beenB. To beC. BeD. Being

发布时间：2020-08-15 00:04:12

     a good insulator , rubber is often used in cables.
A. Having been
B. To be
C. Be
D. Being

网友回答

A. Having been
B. To be
C. Be
(答案→)D. Being
解析：现在分词短语表原因。
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