时间:2021-06-15 09:52 来源：陕西成考网 点击: 206 次
What's the best way to protect a tender, green seedling from the hungry stomach of deer? Give the seedling bad breath!
The same chemical that gives people bad breath after they have eaten garlic can save small trees from being eaten by animals.
A kind of chemical selenium(硒), which is also found in garlic, is planted in the soil near a young tree. The tree's roots absorb the selenium which is then carried to the leaves.
From there the selenium is used to form a chemical called dimethyl selenide (乙烷硒化物)-the same chemical made in the human mouth after eating garlic. As deer wander around looking for food, they smell the seedlings' leaves and leave the plants alone.
The selenium is important. Why? Because each year deer eat millions of dollars' worth of trees farm seedlings.
So far, selenium has been tested only on Douglas fir (枞树) seedlings, but researchers think they could protect fruit trees and garden plants, too.
61. When people eat garlic, ________.
A. they send out a horrible smell B. they are out of breath
C. they will feel sick D. it is hard for them to breathe
62. According to this passage the bad smell given off from those leaves is that of ______.
A.the young trees absorb garlic
B.the roots of the young trees smell like garlic
C.the young trees aren't fit for the deer to eat
D.the leaves of the young trees smell like garlic
64. Up till the time the news was announced, this kind of chemical was used _______.
A. all over the world B. all over the United States
C. on fruit trees and garden trees D. on Douglas fir young trees
65. The best title of this passage is ________.
A. Hungry Deer and Young Trees B. Why Don't Deer Eat Young Fruit Trees
C. Plants Saved by 'Bad Breath' D. How to Protect Young Trees