填空题
[听力原文]11-15
Men are the cleverest and most dangerous animals on earth. Rats come second. Men kill their enemies. They have killed millions of men since ancient times-but rats have killed hundreds of millions of men. Rats carry diseases. Black rats carry a fatal disease called plague which still kills thousands of Asians and Africans today—as it killed millions of Europeans in the past, until brown rats came to Europe and pushed black rats out. There is no plague in Europe today, but brown rats carry 35 other diseases. Rats are dangerous. They not only carry diseases into men’s homes, they also take men’s food. They eat 33 million tons of grain every year. That is enough grain to feed’ 200 million people—so men die of hunger because rats eat their food. Rats are clever, too. They have good leaders. Men try to poison them, but if their leaders tell them that food is dangerous they do not eat it. So our cities and villages are full of rats. We can go to the moon, but we cannot kill this dangerous enemy. Why Is it because we axe not clean