题目

Two ____ students ____ to the opening ceremony last Friday.A. hundreds; were invited B. hundred; were invitedC. hundreds of ; invitedD. hundred of; invited 答案：【答案】B【解析】试题分析：句意：上周五邀请了两百学生参加开业庆典。表示实指时，hundred, thousand，million用单数，后面不跟介词of；表示虚指时，hundred, thousand，million用复数，前不加数词，后跟介词of。本句表示实指：两百。主语students是谓语动作invite的承受者，句子用被动语态。故选B。根据楞次定律可知，感应电流的磁场一定是（　　）A．与引起感应电流的磁场方向相反B．与引起感应电流的磁场方向相同C．阻碍引起感应电流的磁通量D．阻碍引起感应电流的磁通量变化