第四节：阅读理解（共20小题，每小题2分，满分40分）
阅读下列短文,从每题所给的四个选项(A、B、C和D)中,选出最佳选项。
Science Daily -------- Dutch ecologist Roxina Soler and her colleagues have discovered that subterranean（地下的）and above ground herbivorous（食草的）insects can communicate with each other by using plants as telephones. Subterranean insects issue chemical warning signals through the leaves of the plant. Thus, aboveground insects are warned that the plant is already “ occupied”.
Aboveground, leaf-eating insects prefer plants that have not yet been occupied by subterranean root-eating insects. Subterranean insects send out chemical signals through the leaves of the plant, which warn the aboveground insects about their presence. This message makes it possible for two different kinds of insects to avoid each other, so that they do not compete for the same plant.
In recent years it has been discovered that different types of aboveground insects develop slowly if they feed on plants that also have subterranean residents and vice versa（反之亦然）. It seems that a system has developed through natural selection, which helps the subterranean and aboveground insects to communicate with each other. This avoids unnecessary competition.
Through the “green telephone lines”, subterranean insects can also communicate with a third party, namely the natural enemy of caterpillars（毛虫）. Parasitic wasps（寄生的黄蜂）lay their eggs inside aboveground insects. The wasps also benefit from the signals sent by the leaves, as these help them find more insects for their eggs. The communication between subterranean and aboveground insects has only been studied in a few systems. It is still not clear how widespread this phenomenon is.
This research was carried out at the Netherlands Institute for Ecology by Roxina Soler, Jeffrey Harvey, Martijn Bezemer, Wim van der Putten and Louise Vet. The phD project, in which this study was carried out, was funded by the Free Competition of NOW Earth and Life Sciences.
41. After finding a plant occupied by root-eating insects, aboveground insects will usually ________.
A. send out warning signals
B. choose to leave the plant
C. fight with the root-eating insects
D. compete with them for the same plant
42. Aboveground insects will develop more quickly if their food plants _______.
A. have more green leaves
B. get more water and sunlight
C. are often visited by parasitic wasps
D. are not occupied by root-eating insects
43. The underlined part “a third party” in Paragraph 4 refers to ______.
A. caterpillars               B. root-eating insects    
C. parasitic wasps          D. aboveground insects
44. What is the best title for the passage ?
A. Insects use plants as “telephones”
B. How do animals avoid competition
C. The living habit of different insects
D. Communication between different insects