题目内容
Researchers from the University of Haifa-Oranim have managed to make out the "self-irri-gating" mechanism (构造) of the desert rhubarb,which enables it to harvest 16 times the amount of water than otherwise expected for a plant in the Negev Desert. This is the first example of a selfirrigating plant worldwide.
The desert rhubarb grows in the mountains of Israel's Negev Desert,where the average rainfall is particularly low (75 mm per year) . Unlike most of the other desert plant species,which have small leaves so as to reduce water loss,this plant is unique in that its leaves are par?ticularly large.
Professor Simcha Lev-Yadun,Professor Gidi Ne'e man and Professor Gadi Katzir came across this unique plant while studying the field area,and noticed that its waxy leaves are unusually large. They observed a ridged (成脊状的) structure on each leaf.
The scientists explained that these deep and wide depressions (凹陷) in the leaves create a "channeling" mountainlike system by which the rain water is channeled toward the ground sur?rounding the plant's deep root. Other desert plants simply absorb the rain water that goes through the ground in its immediate surroundings.
The findings have shown that the natural selection process has resulted in the evolution of this plant's extremely large leaves,which improved its ability to survive in the arid climate of the desert. The results of experiments and analysis of the plant's growth―in an area with an average annual rainfall of 75 mm―showed that the desert rhubarb is able to harvest quantities of water that are 16 times the amount of water harvested by the smallleafed plants of the Negev Desert. When the research team watered the pJant artificially,they observed how the water flows along the course of the leaves' depressions to the ground surrounding the plant's single root and then goes through the ground to a depth of 10 cm or more. Under the experimental condi?tions,water goes through the ground only as deep as 1 cm. "We know of no other plant in the deserts of the world that functions in this manner," the researchers concluded.
( ) 1. What is the best title for this passage?
A. How Plants' "Selfirrigating" Mechanism Works
B. How Plants Growing in the Desert Survive
C. A Desert Plant Growing in the Negev Desert
D. The World's First " Selfwatering" Plant Is Discovered
( ) 2. The desert rhubarb's "selfirrigating" mechanism .
A. enables it to survive with fewer leaves
B. works in many desert plants in the world
C. helps it absorb much more water than other plants
D. prevents the plant from losing water and heat
( ) 3. Which of the following helps most desert plants adapt to the dry climate?
A. Thin roots. B. Small leaves.
C. Deep depressions. D. Ridged structures.
( ) 4. What can we conclude from the passage?
A. The discovery of the desert rhubarb surprised the researchers.
B. The desert rhubarb causes Israel's Negev Desert drier.
C. The smallleafed plants aren't able to survive in the desert.
D. The research team studied the desert rhubarb in the lab.
1-4 DCBA
A篇：以色列内盖夫沙漠中生存着一种奇特的植物——沙漠大黄能够用自己的叶子给自己浇水。
1. D主旨大意题。本文介绍了一个植物新发现——沙漠大黄，它能够用自己的叶子给自己浇水，故答案为D.
2. C细节理解题。根据第一段"...which enables it to harvest 16 times the amount of water than otherwise expected for a plant in the Negev Desert."可知答案为C。
3. B推理判断题。根据第二段"...Unlike most of the other desert plant species,which have small leaves so as to reduce water loss…"可推断答案为B.
4. A推理判断题。根据末段"We know of no other plant in the deserts of the world that func?tions in this manner"可推断，答案为A.
