题目内容
What chiefly distinguishes essays from articles may be in ______.
查看答案
搜索结果不匹配？点我反馈
更多问题
听力原文： Rats are the enemy of human beings. They eat or spoil crops of grain and rice before they can be harvested, or while they are in storage. In India, where millions of people go hungry, there are ten times as many rats as people. Rats devour half of the available food. Rats will also attack birds and animals, from frogs and chicks to geese and young calves. They have even destroyed dams and buildings by making holes through or under them, and have started fires by chewing on electrical wiring.
The most terrible destruction caused by rats, however, has come from the diseases they carry. In the fourteenth century, rats caused the death of one-third of the world's population by transmitting the dreadful Black Plague that mined Europe.
Ironically, it is in fighting diseases that rats have been most useful to humanity. Thousands of specially bred rats are used in research laboratories every year to test medicines which can possibly be used to prolong and improve human life. Some laboratory rats are even used to test new methods of eliminating their cousins, the wild rats.
(23)
A．Take the woman to her home.B．Test-drive the woman's car.C．Help the woman pay the mec
A．withB．inC．forD．at
Task 2
Directions: This task is the same as Task 1. The 5 questions or unfinished statements are numbered 41 through 45.
Why don't birds get lost on their long flights from one place to another？ Scientists have puzzled over this question for many years. Now they are beginning to fill in the blanks.
Not long ago, experiments showed that birds depend on the sun to guide them during day-flight hours. But what about birds that fly by night？ Tests with man-made stars have proved that certain night-flying birds are able to follow the stars in their long-distance flights.
A dove spent its lifetime in a cage and had never flown under a natural sky. Yet it showed an inborn ability to use the stars for guidance. The bird's cage was placed under a man-made star-filled sky. The bird tried to fly in the same direction as that taken by his outdoor cousins. Any change in the position of the make-believe stars caused a change in the direction of his flight.
Scientists think that doves, flying ill daylight, use the sun for guidance. But the stars are obviously their most important means of navigation (or flying). What do they do when the stars are hidden by clouds？ Obviously, they find their way by such landmarks as mountains ranges, coastlines, and river courses. But when it is too dark to see these, the doves circle helplessly, unable to get their bearings.
The reason why birds don't get lost on long flight ______.
微信支付 
支付宝支付