4、Wild elephants that destroy crops and damage trees are a serious problem in many parts of Africa . But there could be a simple and relatively safe way to stop them in their tracks , by employing the talents of the tiny African honeybees .

       The number of elephants in Kenya has risen over the past ten years , with some disastrous results . Not only do these huge animals attack local farms , but they step someone to death an average of once every two weeks . Now a biologist has discovered a possible threat : the elephants are extremely aware of trees that house honeybee hives .

       “I an puzzled why nobody has thought of this before , ” says Fritz Vollrath at the University of Oxford . “ When an elephant knocks a beehive he runs and the bees will follow him or miles . ” He says that placing hives of the honeybees around local farms and fragile habitats could be an effective way to threaten the animals .

       Volirath put 30 unoccupied and 6 occupied beehives in some of the growing on a bush frequently damaged by elephants on Laikipia Plateau in Kenya . On average the elephants attacked 9 out of 10 trees that didn’t have hives , severely damaging a quarter . But they steered clear of all six trees with occupied hives . The elephants also left alone one-third of the trees with empty hives , suggesting that some had learnt not to take the risk .

       The bees threaten elephants by stinging vulnerable (易受傷)areas such as the eyes , belly , behind the ears and under the trunk . People could be at risk from the bees , admits Voilrath , but that may be outweighed by the risk of being killed by an elephant . Another experiment by Voilrath shows that elephants also avoid the sound of angry bees played from a loudspeaker .

1．What harm do the wild elephants in Africa do ?

       A．Killing local people                                     

B．Damaging beehives

C．Threatening animals                                   

D．Destroying villages

2．What can we learn from the underlined sentence ?

       A．They ran away from the trees with empty hives on it

B．They tried not to touch the trees with hives full of bees

C．They kept a distance from al the trees with hives on them .

D．They were clear that all the six trees were occupied by hives

3．What’s Volirath’s another experiment on this elephant’s case ?

       A．Let bees attack and kill elephants one by one

B．Encourage bees to sting elephants’ eyes and ears

C．Use the bees’ sound to drive elephants away

D．Employ tiny African honeybees to threaten elephants

4．From the passage we can conclude that _______

       A．there is always one thing to bet another

B．little bees can kill big and wild elephants

C．serious problems often come up in Africa

D．elephants enjoy attacking people and farms