题目

Please __________why you're so late, said his girlfriend. A. excuse       B. explain       C. apologize       D. tell 答案：B17．把生铁冶炼成钢，目的是（　　）A．改善性能，增大用途B．除去硫、磷和过多的碳，调整合金元素的含量C．副产磷肥、水泥等D．用红棕色炉气制取水煤气