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问题 选择题

如图所示，图中事例不存在弹力的是

               

A拉力器       B跳水           C射箭    D磁铁改变铁球运动方向

答案

答案：D

题目分析：A、人拉弹簧拉力器时，弹簧变长发生形变，会产生弹力，不符合题意；

B、跳板在人的压力作用下弯曲，发生形变，会产生力的作用，不符合题意；

C、拉弓射箭时，弓发生形变，会产生弹力作用，不符合题意；

D、磁铁对小球的引力是磁场力，不是弹力，在该事例中不存在弹力，符合题意；

故选D．

点评：本题考查了判断是否有弹力产生，看物体是否发生形变是判断弹力有无的关键．

单项选择题

Most plants can make their own food from sunlight, (1) some have discovered that stealing is an easier way to live. Thousands of plant species get by (2) photosynthesizing, and over 400 of these species seem to live by pilfering sugars from an underground (3) of fungi(真菌). But in (4) a handful of these plants has this modus operandi been traced to a relatively obscure fungus. To find out how (5) are (6) , mycologist Martin Bidartondo of the University of California at Berkeley and his team looked in their roots. What they found were (7) of a common type of fungus, so (8) that it is found in nearly 70 percent of all plants. The presence of this common fungus in these plants not only (9) at how they survive, says Bidartondo, but also suggests that many ordinary plants might prosper from a little looting, too.

Plants have (10) relations to get what they need to survive. Normal, (11) plants can make their own carbohydrates through photosynthesis, but they still need minerals. Most plants have (12) a symbiotic relationship with a (13) network of what are called my corrhizal fungi, which lies beneath the forest (14) . The fungi help green plants absorb minerals through their roots, and (15) , the plants normally (16) the fungi with sugars, or carbon with a number of plants sharing the same fungal web, it was perhaps (17) that a few cheaters—dubbed epiparasites—would evolve to beat the system. (18) , these plants reversed the flow of carbon, (19) it into their roots from the fungi (20) releasing it as "payment.\

2（）

A.for

B.with

C.to

D.without
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单项选择题

开始有关检查性交谈时应注意的问题中哪项不合适（）

A.以诚恳、体贴、关心的态度对待病人，让病人情绪放松，消除顾虑

B.提供安静、不受干扰的交谈环境

C.请病人就座，倒茶、递烟，取得病人的好感

D.医生做适当的自我介绍，为医患关系定下一个平等的基调

E.检查前应对病史有一个大致的了解，以利于询问时有的放矢
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