单选题 {{B}}Directions:{{/B}} Read the following text. Choose the best word(s) for
each numbered blank and mark A, B, C or D on ANSWER SHEET 1.
Most plants can make their own food
from sunlight,{{U}} (1) {{/U}}some have discovered that stealing is an
easier way to live, Thousands of plant species get by{{U}} (2)
{{/U}}photosynthesizing, and over 400 of these species seem to live by
pilfering sugars from an underground{{U}} (3) {{/U}}of fungi(真菌). But
in{{U}} (4) {{/U}}a handful of these plants has this modus operandi been
traced to a relatively obscure fungus. To find out how{{U}} (5)
{{/U}}are{{U}} (6) {{/U}}, mycologist Martin Bidartondo of the
University of California at Berkeley and his team looked in their roots. What
they found were{{U}} (7) {{/U}}of a common type of fungus, so{{U}}
(8) {{/U}}that it is found in nearly 70 percent of all plants. The
presence of this common fungus in these plants not only{{U}} (9)
{{/U}}at how they survive, says Bidartondo, but also suggests that
many ordinary plants might prosper from a little looting, too.
Plants have{{U}} (10) {{/U}}relations to get what they need to
survive. Normal,{{U}} (11) {{/U}}plants can make their own carbohydrates
through photosynthesis, but they still need minerals. Most plants have{{U}}
(12) {{/U}}a symbiotic relationship with a{{U}} (13)
{{/U}}network of what are called mycorrhizal fungi, which lies beneath the
forest{{U}} (14) {{/U}}. The fungi help green plants absorb minerals
through their roots, and{{U}} (15) {{/U}}, the plants normally{{U}}
(16) {{/U}}the fungi with sugars, or carbon. With a number of plants
sharing the same fungal web, it was perhaps{{U}} (17) {{/U}}that a few
cheaters—dubbed epiparasites—would evolve to beat the system.{{U}} (18)
{{/U}}, these plants reversed the flow of carbon,{{U}} (19) {{/U}}it
into their roots from the fungi{{U}} (20) {{/U}}releasing it as
"payment."