单项选择题
A．rats killed thousands of Asians and Africans B．rats carry diseases on to the moon C．rats survive the poison food D．rats eat millions of tons of grain each year
A．rats have clever leaders B．rats are clever than men C．rats steal men's food D．rats killed hundreds of millions of men
A．take men's food B．live in cities and villages C．know how to identify poison food D．all of the above