单选题 {{B}}Directions:{{/B}} Read tile 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 my
corrhizal 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."