将a、b、c三种金属分别投入稀盐酸中，只有b溶解并产生气泡；把a和c分别放入硫酸铜溶液中，在a表面有铜析出，c没有变化。则a、b、c的金属活动性顺序是

A．c＞b＞a

B．b＞a＞c

C．a＞c＞b

D．b＞c＞a

Our teacher asked me ________.

A．what was Ann doing these days

B．why didn’t Peter come to school the day before

C．when will the dolphin show begin

D．how long I usually spent on my homework