20、Men are the cleverest and most dangerous animals on the earth．Rats come second．Men kill many other animals．They kill their enemies(敌人)．They have killed hundreds of millions of men．Rats carry many diseases, and these diseases have killed and are still killing thousands of men today in many countries．Rats are dangerous not in only one way．They not only carry diseases into men's homes, but also they eat up men's food．They eat 33 million tons of grain every year．That is enough grain to feed 200 million people．Rats are clever, too．They have good leaders．Men try to poison(毒) them, but if their leaders tell them that the food is dangerous, they don't eat it．

Our cities and villages are full of rats today．We can go to the moon, but we are not able to kill all these rats today．Is it because this dangerous enemy is too clever and grows fast, or we are not clever enough as well as not clean enough?

1．                     , so they are the most dangerous．

A．Men often eat animals                              B．Men never love animals

C．Men feed on meat                                   D．Men kill a lot of enemies

2．How do rats kill men?

A．They have leaders．                                B．The diseases they carry kill men．

C．They eat little babies．                            D．They eat much grain．

3．Rats eat a lot of grain, so                     ．

A．many men are hungry                              B．men have to work hard

C．men can't live any longer                         D．men have to leave their hand

4．The leaders of the rats tell the rats                ．

A．to go away from men                              B．to stop eating the grain

C．not to eat the food with poison                 D．to be careful of men

5．Which of he following is TRUE?

A．Rats are cleverer than men．                       B．It is difficult for men to kill rats．

C．Men are the ablest on the earth．                 D．Men will soon be able to kill all the rats.