Part B
Until about two million years ago Africa’s vegetation had always been controlled by the interactions of climate; geology, soil, and groundwater conditions; and the activities of animals. The addition of humans to the latter group, however, has increasingly rendered unreal the concept of a fully developed "natural" vegetation-- i. e. , one approximating the ideal of a vegetational climax. (41) _____________________. Early attempts at mapping and classifying Africa’s vegetation stressed this relationship: sometimes the names of plant zones were derived directly from climates. In this discussion the idea of zones is retained only in a broad descriptive sense.
(42) _____________________. In addition, over time more floral regions of varying shape and size have been recognized. Many schemes have arisen successively, all of which have had to take views on two important aspects: the general scale of treatment to be adopted, and the deg
Part B
Until about two million years ago Africa’s vegetation had always been controlled by the interactions of climate; geology, soil, and groundwater conditions; and the activities of animals. The addition of humans to the latter group, however, has increasingly rendered unreal the concept of a fully developed "natural" vegetation-- i. e. , one approximating the ideal of a vegetational climax. (41) _____________________. Early attempts at mapping and classifying Africa’s vegetation stressed this relationship: sometimes the names of plant zones were derived directly from climates. In this discussion the idea of zones is retained only in a broad descriptive sense.
(42) _____________________. In addition, over time more floral regions of varying shape and size have been recognized. Many schemes have arisen successively, all of which have had to take views on two important aspects: the general scale of treatment to be adopted, and the deg
Until about two million years ago Africa’s vegetation had always been controlled by the interactions of climate; geology, soil, and groundwater conditions; and the activities of animals. The addition of humans to the latter group, however, has increasingly rendered unreal the concept of a fully developed "natural" vegetation-- i. e. , one approximating the ideal of a vegetational climax. (41) _____________________. Early attempts at mapping and classifying Africa’s vegetation stressed this relationship: sometimes the names of plant zones were derived directly from climates. In this discussion the idea of zones is retained only in a broad descriptive sense.
(42) _____________________. In addition, over time more floral regions of varying shape and size have been recognized. Many schemes have arisen successively, all of which have had to take views on two important aspects: the general scale of treatment to be adopted, and the degree to which human mod
| About one million years ago, the Ice
Age began. The Ice Age was a long period of time in which four great glaciers
pushed southward to cover almost all the upper half of North America, and then
melted away. Each glacier was a thick sheet of ice and snow that spread out from
a centre near what is now Hudson Bay in Canada. The winters were long, and the
cool summers were too short to melt much of the ice and snow. The ever-growing
sheet built up to a thickness of two miles at its centre. As all glaciers do, these great glaciers slid. They pushed down giant trees in their paths and scraped the earth bare of soil. Many animals moved farther south to escape. Others stayed and were destroyed. When winters of little snow came, the summer sun cut into the edges of the ice sheets. As the glaciers melted, rocks, soil and other things A. the Ice Age was a long period of time B. great glaciers covered North America many years ago C. changes in climate helped to melt the glaciers D. how glaciers changed North America [简答题] About three hundred years ago in Italy, there lived a young man whose name was Galileo. He was always thinking and always asking the reasons for things.
One evening when he was only eighteen years old he was in the cathedral at Pisa at about the time the lamps were lighted. From the (47)________lamps were hung by long rods. (48)________ the lamplighter knocked against them, or the wind blew through the (49)______ they would swing back and forth like pendulums. Galileo noticed this, then he began to study them more closely. As Galileo watched them swinging to and fro he became much (50)______.
When he went to his room he began to (51)______ He took a number of cords of different (52)______ and hung them from the ceiling. To the free end of each cord he fastened a weight. Then he set all to swinging back and forth, like the (53)______ in the cathedral. Each cord was a pendulum, just as each rod had been.
(54)______, to the swinging lamps in the cathedral, and to Galile
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