题目钢与铁是以含碳量（ ）为分界线。A. 0.77%B. 0.0218%C. 2.11%D. 4.3%钢与铁是以含碳量（ ）为分界线。A. 0.77%B. 0.0218%C. 2.11%D. 4.3%题目解答答案C. 2.11%