单选题 ______, it is quite easy to drill a hole on it with laser.
  • A. Hard although the diamond is
  • B. How hard is the diamond
  • C. As the diamond is hard
  • D. Hard as the diamond is
【正确答案】 D
【答案解析】[解析] 英语中让步状语从句可用“形容词+as+主语+谓语”倒装结构表示，故选D，其他选项不合适。句意为：虽然钻石很硬，但用激光很容易在其上面钻洞。