目前我国荒漠化土地面积为262.2万平方千米，约占国土面积的27.3％，而且荒漠化土地面积仍以每年2460平方千米的速度扩展，吞噬着我们许多可利用的土地。据此回答下题。我国受荒漠化影响较大的省级行政区有

A．新疆维吾尔自治区、内蒙古自治区

B．湖北省、湖南省

C．广东省、海南省

D．浙江省、江西省

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