There are currently three living species of elephants： the African Bush Elephant, the African Forest Elephant and the Asian Elephant or Indian Elephant. Other species such as the mammoths （猛狙象）1______ before the last ice age but are now 2 ______.
Elephants live in a structured social order. 3______ females spend their entire lives in tight- knit family groups 4______ mothers, daughters, sisters and aunts, males live mostly solitary lives. Elephants 5 ______ live for 50 to 70 years. The elephant's pregnant period is 22 months, the longest of 6 ______ land animal. Newborn elephant calves weigh 7______260 pounds.
Elephants spend about 16 hours a day finding and eating food. Their diet consists 8______ grasses, leaves, bamboo, twigs, bark, roots and small amounts of fruits, seeds and flowers.Interestingly, elephants only digest 40% of 9______ they eat； an adult elephant can consume 300-600 lb of food a day.
Elephant skin is thick, grey and wrinkled. The wrinkles help elephants stay cool 10______ water gets trapped inside the wrinkles and evaporates slowly. Their hearing is 11______ and they can detect noise from miles away.
One of the most distinct 12______ attributes of elephants is their tusks. Elephants use their tusks to dig for food, mark their 13______ and perform other tasks. Elephants' tusks are made of ivory. The 14______ elephant ivory is one of the major reasons people hunt elephants and thus have significantly 15______ the world's elephant population. For this reason and many others. many people around the world are working hard to protect the species from further extinction.
3
A.When
B.While
C.As
D.Since
正确答案是B