練習：
1 .Why are ants compared to ecosystem engineers?
A Because they build their own nests.
B Because they collect food.
C Because their activity affects the environment.
D Because they are predators.
2. As predators， ants
A prey on small as well as large animals.
B collect nutritious food from the soil
C collect food as decomposers.
D prey on species much higher up the food chain.
3. Dir Sanders study centered on how ants
A can manage to thrive in huge numbers.
B defend their resources and territory against other predators.
C attack those invading animals for survival.
D produce such a big impact on the environment.
4. What does paragraph 6 tell us?
A Ants bring about a negative influence to an area when their population is small.
B Ants bring about a positive influence to an area when their population is small.
C Ants predation counteracts the positive influence they may have on an area.
D At higher density， ants produce a positive influence on an area.
5. What still remains unclear about ants， according to the last paragraph?
A What roles do ants play in the ecosystem in which they live?
B How do ants affect the animal diversity in a given ecosystem?
C How do human activities affect ants influence on a given ecosystem?
D How do ants alter the physical and chemical environment?
答案與題解：
1. C 短文的第一段提供了答案。A不是正確答案，因為并不是因為螞蟻會筑巢才被譽為生態系統工程師，而是因為它們筑巢和獲取食物的方式改變了土壤的營養水平，為整個食物鏈提供了很好的生態環境(見第二段)。
2.A答案能夠從短文的第三段直接找到。該段告訴我們，螞蟻的掠食范圍很廣，甚至包括比它們體積更大的動物( larger animals) 。 prey 在這里的意思是"捕獵，捕食"，作為動詞，后面跟介詞on或upon.
3.D Dirk Sanders說："In this research， we studied for the first time how big this impact is and the subtleties of it."(第五段)所以，D是正確選擇。句中the subtleties of it 的意思是：螞蟻對環境影響的精妙之處。
4.B 短文第六段第二句的大概意思是，螞蟻數量小(a low density of ants)的話，能使其他動物的品種和數量增加(increased the diversity and density of other animals)，從而給環境帶來積極影響；第三句說，如果螞蟻的數量大(At higher densities)，就不可能產生同樣的影響，或者是相反的影響，這表明，螞蟻的掠食活動會抵銷螞蟻給環境帶來的積極影響。第七段Dr Frank van Veen 表達了大體相同的內容。
5.C 最后一段的第二和第三句提供了答案。第二句告訴我們，螞蟻極易受人類的影響(these organisms are highly responsive to human impact)，第三句告訴我們，科學家還不清楚人類對螞蟻這種干擾如何破壞螞蟻對生態系統的維護作用("it is not clear how such disturbance damages the maintenance of ant services to the ecosystem.")。