When Dr． Karen McComb came to Amboseli Park， her first task was to learn the names of the one hundred or so elephants most often seen．

    Scientists working in the park have learned to study elephants by watching them up close． They have a list of almost one thousand elephants． There are records for all of the elephants born since 1972． Amboseli was a good place for Dr． McComb to study animal communications． Elephants were a great subject because their lifestyle depends on communication．

    Dr． McComb and her team had learned a lot about elephant communication， but they kept on thinking about one puzzling （困惑的） watch． Some families were better at distinguishing （区别） calls of friends from those of strangers．

    What made some families smarter than others？ The scientists searched their records for an explanation． To their surprise， there was only one factor （因素） of importance： The "smartest" families always had the oldest grandmothers． A family， as it did in all other activities， waited for some signal （信号） from the grandmother when they heard a strange contact call． And older， more experienced grandmothers were better at telling whether other elephants were strangers or friends just by their calls．

    That was an important discovery． It showed how an elephant family depends on the experience of the grandmother．

回答下面5个问题，每题答案不超过5个词．

（1）How do scientists working in the park study elephants？　　

（2）What did Dr． McComb study？　　

（3）What did Dr． McComb and her team do for an explanation？　　

（4）Who does everyone in elephant families listen to？　　

（5）What does an elephant family depend on in all the activities？