单项选择题
A．they carry fleas which give men bubonic plague B．they come with typhus C．they carry thirty-five diseases D．they killed 200 million people
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