题目

0.9 g某元素的单质直接跟氯气反应后，质量增加了3.55 g，这种元素是(    ) A.P                        B.Mg                           C.Al                         D.Fe 答案：C 解析：设该金属为R，氯化物化学式为RClx。则 ，,代入检验可知该金属为Al。— Why is Mr. Yang still in the teachers' office?— Maybe he ______ his work yet.A.doesn't finishB.hasn't finishedC.haven't finished