更多"Why was it possible for these ancie"的相关试题:
[单项选择]Why was it possible for these ancient trees let more light through than modern ones
A. Because they were closely spaced, only 3 to 16 feet apart.
B. Because they were smaller plants and shrubs.
C. Because their branches did not fan out as far as to form a shape like umbrella.
D. Because they had very small leaves like that of fern and dropped easily.
[单项选择]According to the passage, cutting trees to grow more food______.
A. will widen the gap between the developed and the developing countries
B. is but a short-term relief to the food problem
C. can hardly alleviate the shortage of food
D. proves to be an effective way out for impoverished nations
[单项选择]Why did people cut down trees
A. For advantage.
B. For benefit.
C. For house.
D. For business.
[单项选择]Why researchers put trees in extra carbon dioxide in the first study
A. To learn whether trees can still absorb carbon dioxide under extreme conditions.
B. To get more oxygen from these trees.
C. To evaluate the maximum carbon dioxide that trees can absorb.
D. To see the growth rate of these trees.
[单项选择]Why do some people think hemp is better than trees for paper industry
A. It is cheaper to grow hemp than to cut down trees.
B. More paper can be produced from the same area of land.
C. Hemp planting can beautify the environment.
D. Hemp can produce paper of high quality.
[单项选择]Why is the mixed planting of trees of the same species advocated in modern orchards and forests
A. Because mixed forests and orchards are the recognized procedures these days.
B. Because trees of same species may spread disease.
C. Because orchards and forests are modern.
D. Because trees planted crowdedly do not have enough room to develop their roots.
[单项选择]Why is the close planting of trees of the same species avoided in modern orchards and forests
A. Because mixed forests and orchards are the recognized procedures these days.
B. Because trees of same species may cause the spread of disease.
C. Because modern orchards and forests are more specialized.
D. Because trees planted crowdedly do not have enough room to develop their roots.
[单项选择]The reason why the electric eel is able to give more powerful shock is that______.
A. the working system of the electric plates in the eel is the most effective
B. the working system of the electric plates in the eel is far inferior to those in the torpedo
C. compared with those in the torpedo, the working system of electric plates in the eel is more direct and efficient
D. compared with other electric fish, the eel possesses much more electric plates
[单项选择]Why is it advised to buy a baby dog under three months old
