789亿改写成以“一”为单位的数是______．
题型：填空题
问题：
789亿改写成以“一”为单位的数是______．
题型：填空题
阅读理解。
Elephants don't forget-at least, female (雌性的) elephants don't. Elephant families are matriarchal. And
the social knowledge gained by the oldest females is the key to a family group's survival (生存), according
to a study published in April by Karen McComb, a biologist at Sussex University in England.
Elephants announce their presence by making a deep, long sound, a practice referred to as contact calling
(联络呼叫). An unfamiliar call may mean that an elephant from outside the family group is nearby. A stranger
can cause trouble. Interrupting feeding or disturbing the young. So an elephant matriarch signals the family to
gather around her; then they all lift their trunks in the air to smell the unfamiliar caller. False alarms can disturb
the group and take time and energy away from feeding, so survival may depend in part on getting it right.
Working with Cynthia Moss, who founded the Amboseli Elephant Research Project in Kenya 30 years ago,
McComb tested the social knowledge of 21 Amboseli elephant families with matriarchs 27 to 67 years old. She
played recordings of contact calls to each family and found that the oldest matriarchs were much better at
picking out unfamiliar calls. In fact, a group with a matriarch in her fifties was several thousand times more
likely to form into a group upon hearing an unfamiliar contact call than when hearing a familiar call. However,
families with younger matriarchs were less than twice as likely to gather together upon hearing an unfamiliar
contact call as compared with a familiar call. And they gathered together a lot. Moreover, the social knowledge
of older matriarchs translated into favourable results: Families with older matriarchs produced more baby
elephants in each female-reproductive year.
This finding shows how difficult it is to protect the oldest members of elephant families. As elephants age,
they continue to grow larger,as do their much wanted tusks (象牙). So the older-and wiser-a matriarch is, the
greater the chance she will be killed. About 800,000 elephants have been killed by people in the past 20 years.
1. What does the underlined word "matriarch" mean?
A. An old member of an elephant family.
B. A female head of an elephant family
C. A wise elephant.
D. A large elephant.
2. When do elephants form into a group?
A. When they are feeding the young.
B. When they see a familiar elephant.
C. When they are giving birth to baby elephants.
D. When the leading elephant gives out a warning.
3. The research with recordings of contact calls shows _____.
A. how fast elephants form into groups
B. how important the age of a leading elephant is
C. how frightened elephants are when hearing a strange call
D. how frequently old elephants call other members of the family
4. The older a female elephant is, _____.
A. the stronger she will be
B. the poorer memory she will have
C. the more useless her tusks will be
D. the more likely she will be killed
5. We can infer from the passage that elephants may _____.
A. run into other elephant families
B. give wrong warnings to their mothers
C. run away open hearing a strange sound
D. produce more babies by gathering together often