| Lichens may grow on the bark of a tree in a steaming tropical rain forest, on the bricks of big city buildings, on rocks in hot springs, on wind-swept mountaintops, and in the driest desserts. In the arctic, they provide the principal food for caribou, and they are one of the few plants that grow in Antarctica. They are pioneers, appearing in barren rocky areas and starting the formation of soil in which mosses, then ferns, and then other plants can take root. Lichens are a partnership of two plants — fungi and algae. The lichen body is made up of a network of fungal strands. In the upper layers of these grow groups of algae. The two organisms live together to the benefit of both, a relationship known as symbiosis. The fungi provide support, absorb water, and shelter the tender algae from direct sunlight. The algae carry on photosynthesis and provide the fungi with food. The algae can live independently and are recognizable as a species that grows alone. The fungi, on the other hand, cannot live apart from their partners. They can be placed in known classes of fungi but are unlike any species that lives independently. So definite are the form, color, and characteristics of these double organisms that for hundreds of years, they were classified as one. More than 15,000 "species" were named. If these organisms are classified as separate species, it is difficult to fit them into the existing system of classification. But if they are classified separately, these species of fungi seem rather strange. Lichens are a splendid example of the difficulties faced by taxonomists in classifying species. |
The word "barren" underlined in Paragraph 1 most probably means _______ .
A．lifeless
B．frigid
C．hard
D．uncovered
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I'll let my brother _____ you.[ ]
A. help
B. to help
C. helps
下列有关著作权的表述正确的是( )。
A．对著作权中的财产权的保护不受期限限制
B．对著作权中的人身权的保护不受期限限制
C．作者死亡后，其著作权由其继承人继承
D．作者死亡后，著作权中的财产权可由其继承人继承
脾（）
A、位于右季肋区
B、长轴与肋弓一致
C、上缘有2一3个脾切迹
D、为腹膜外位器官
E、属于消化系统
现在用的国内销售价格手册中规定，儿童票价是成人适用销售价格的（）。
A.75%
B.50%
C.10%
D.60%
某井发生溢流关井，套压继续上升，已接近最大允许关井套压值，采取措施为（）。
A.通过放喷管线适当放喷减压
B.敞开井口放喷
C.憋漏地层，保护环境，保护设施