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问题 选择题

Mrs Smith has a cute baby. It often smiles at people ________. [ ]

A. friendly

B. lovely

C. happily

D. lively

答案

答案：C

单项选择题 案例分析题

一轴心受压砖柱，截面尺寸为370mm×490mm，两端为不动铰支座，H0=H=3.5m，材料强度等级为烧结普通砖MU10，砂浆采用混合砂浆，砖砌体自重19kN/m3。若柱顶截面上作用由恒载和活载产生的轴向力设计值为200kN，施工质量控制等级为B级。

若混合砂浆的强度等级为M5，则柱底截面的轴心受压承载力最接近于（）kN。

A.200.2

B.211.4

C.213.5

D.215.6
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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.\

18（）

A. in time

B. overtime

C. at times

D. behind time
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