题目

 (10·湖南B篇) When Mary Moore began her high school in 1951, her mother told her, Be sure and take a typing course so when this show business thing doesn't work out, you'll have something to rely on. Mary responded in typical teenage fashion. From that moment on, the very last thing I ever thought about doing was taking a typing course, she recalls.      The show business thing worked out, of course. In her career, Mary won many awards. Only recently, when she began to write Growing Up Again, did she regret ignoring her morn, I don't know how to use a computer, she admits.  � 在练习使用多用表的实验中，某同学连接的电路如图（甲）所示。        ①若旋转选择开关，使尖端对准直流电流"50mA"  挡，闭合电键S，指针如图（乙）所示，此时调得的是通过        的电流，其大小为                   mA。        ②若断开电路中的电键S，旋转选择开关使其尖端对准电阻“×l0”挡，按规范步骤操作，指针如同（乙）所示，此时测得R1、R2的总电阻为             。