单选题:根据以下材料,回答 1~5 题:What is the main purpose for Dr. Gray and Dr 题目分类:英语六级 题目类型:单选题 查看权限:VIP 题目内容: 根据以下材料,回答 1~5 题:What is the main purpose for Dr. Gray and Dr. Wegner to conduct the experiment? 参考答案: 答案解析: