---- What are you doing?     ---- I’m ________ my English book.

A．looking after

B．looking at

C．looking for

D．looking like

某人用多用电表按正确步骤测量一电阻的阻值，当选择欧姆挡“×1”挡测量时，指针指示位置如图所示，则其电阻值是______．如果要用这只多用电表测量一个约200欧的电阻，为了使测量比较精确，选择开关应选的欧姆挡是______．改变挡位调整倍率后，要特别注意重新______．