题目

Writing out all the invitations by hand was more time­consuming than we________. A . will expect B . are expecting C . expect D . had expected 答案：D7．酸能与许多物质发生反应．下列变化中，只有加酸才能一步实现的是（　　）A．Fe→FeCl3B．CaO→CaCl2C．CaCO3→CO2D．KOH→KCl