题目

Living abroad to study can certainly be an interesting experience but is that alone a good enough reason for spending years far away from home? To make the experience truly worthwhile, there has to be a goal behind the decision to study abroad. This may be a wish to perfect language skills in a foreign language environment, or a clever move in your career development. You must also consider the costs, not just of living and studying abroad, but of applying. Most universities now charge application fees for international students. If after considering these points you are sure that you （2017唐山路南区一模）对下列物质分类正确的是（　　）A.冰和玻璃都是晶体B.铅笔芯和陶瓷都属于绝缘体C.汞和金刚石都属于金属单质D.塑料、合成橡胶都属于合成材料