题目

纯铁的熔点为1535℃，而在高炉中炼铁时，生铁（含铁量较高铁的合金）在1200℃左右就熔化了，这是因为A.铁的纯度越高熔点越低                 B.合金的熔点比其成分物质的熔点高C.形成了铁碳合金，所以熔点变低         D.在高炉中熔化的过程发生了化学反应 答案：C______ frightened us ______ the electricity was suddenly cut off, which threw all of us into the dark. A. It was; thatB. What was; most was thatC. It; most what D. What; most was that