题目

用括号中所给单词的适当形式填空。【小题1】Now people eat______ (health) than before and many of them pay much attention to doing sports after work. 【小题2】The boy           (take) to hospital at once after he fell off the tree. 【小题3】We must do what we can            (save) the girl. She is too young.【小题4】We hope that more charity shows           __ (hold) to raise money for Project Hope. 【小题5】The boy considered              (he) as the smartest boy in his class.如图2-11所示，直角三角形导线框abc固定在匀强磁场中，ab是一段长为L、电阻为R的均匀导线，ac和bc的电阻可不计，ac长度为L/2.磁场的磁感应强度为B，方向垂直纸面向里.现有一段长度为L/2、电阻为R/2的均匀导体杆MN架在导线框上，开始时紧靠ac，然后沿ab方向以恒定速度v向b端滑动，滑动中始终与ac平行并与导线框保持良好接触.当MN滑过的距离为L/3时，导线ac中的电流是多大？方向如何？图2-11