题目

阅读下面短文，完成相关任务。 Jeff Gaye, the young American swimmer, is becoming more and more famous. He has his own teacher, driver and even his own cook. Each time people hear him speak on television, they can’t believe he’s only 13. Jeff’s father is an engineer but he is also his son’s manager. He says, “I don’t make Jeff do anything he doesn’t want to do. He chooses which competition to swim in. But he works hard and wins nearly every race. I cut out all the newspaper articles about him and put them in a big box!” Jeff is very busy every day because p下列叙述中，因果关系不成立的是A.金刚石是天然存在的最硬的物质，因此可用于裁玻璃B.石墨具有导电性，因此常用于制铅笔芯C.活性炭疏松多孔，有吸附性，可用于防毒面具吸附毒气D.木炭具有还原性，因此用于冶炼金属