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问题 选择题

下列化合物中，不能通过单质间化合直接制取的是（   ）

A．FeCl3

B．CuCl2

C．HCl

D．FeCl2

答案

答案：D

题目分析：铁和氯气直接化合生成氯化铁，得不到氯化亚铁，答案选D。

点评：该题是基础性试题的考查，试题难易适中，侧重对学生基础知识的巩固和检验，难度不大。该题的关键是学生要熟练记住，并能灵活运用。

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.\

15（）

A. in turn

B. in fact

C. in return

D. in the end
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判断题

脊椎的造血时间是晚上11—凌晨3点。
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