题目

某石灰石含碳酸钙80%（不含其它含钙杂质），该石灰石中含钙元素的质量百分含量是        A．42%          B．40%           C．38%          D．32% 答案：D_________ I've been busy these days, I've ________ the price for the computer. [    ] A. But, get out B. And, take out C. Or, look out D. Although, found out