—Were you at home at 9 o'clock last night？
—Yes，I a shower at that time．
A．took B．was taking C．was taken D．am taking
—Were you at home at 9 o'clock last night？
—Yes，I a shower at that time．
A．took B．was taking C．was taken D．am taking
B
【解析】句意：——你昨晚9点在家吗？——是的，那时我正在洗澡。从at 9 o'clock last night判断句子时态是过去进行时，构成were/was+V-ing。故选：B。