When an ant dies, other ants move the dead insect out of the nest. This behavior is interesting to scientists, who wonder how ants know for sure – and so soon-that another ant is dead.
Dong-Hwan Choe, a scientist at the University of California2 found that Argentine3 ants have a chemical on the outside of their bodies that signals to other ants, "I'm dead - take me away."
But there's a twist to Choe's discovery4. These ants are a little bit like zombies. Choe says that the living ants - not just the dead ones - have this death chemical. In other words, while an ant crawls around, perhaps in a picnic or home, it's telling other ants that it's dead5.
What keeps ants from hauling away the living dead? Choe found that Argentine ants have two additional chemicals on their bodies, and these tell nearby ants something like, "wait -I'm not dead yet. "So Choe's research turned up6 two sets of chemical signals in ants: one says, "I'm dead," the other set says, "I'm not dead yet."
Other scientists have tried to figure out how ants know when another ant is dead. If an ant is knocked unconscious, other ants leave it alone until it wakes up. That means ants know that unmoving ants can still be alive.
Choe suspects that when an Argentine ant dies, the chemical that says "Wait- I'm not dead yet" quickly goes away. Once that chemical is gone, only the one that says "I'm dead" is left." It's because the dead ant no longer smells like a living ant that it gets carded to the graveyard, not because its body releases new unique chemicals after death," said Choe. When other ants detect the "dead" chemical without the "not dead yet" chemical, they haul away the body. This was Choe's hypothesis.
To test his hypothesis, Choe and his team put different chemicals on Argentine ant pupae. When the scientists used the "I'm dead" chemical, other ants quickly hauled the treated pupae7 away. When the scientists used the "Wait- I'm not dead yet" chemicals, other ants left the treated pupae alone. Choe believes this behavior shows that the "not dead yet" chemicals override the "dead" chemical when picked up by adult ants. And that when an ant dies, the "not dead yet" chemicals fade away. Other nearby ants then detect the remaining "dead" chemical and remove the body from the nest.
Zombie n 还魂尸，僵尸 Pupa n.蛹
1. night：night 是个多义词，其比喻意义是“死亡”，即本篇短文标题中该词的意思。标 题是用了逆喻的修辞手法。
2. the University of California：加利福尼亚大学，位于美国西部的公立高等学校系统 ，目前拥有10所大学，包括加州大学伯克利分校(Berkeley)、洛杉矶分校( Los Angeles)、 圣地亚哥分校(San Diego)、圣克鲁兹分校(Santa Cruz)等。
4. But there's a twist to Choe's discovery.然而，Choe 又有了新的出乎意料的发现。 Twist 有“出人意料的变化”的意思。
5. 本句 it's telling other ants that it's dead 中两个 it 指代前面爬行中的蚂蚁，也 就是下段第一句中的 the living dead。
6. turned up：发现，找到。
7. treated pupae：经过处理的蛹，即被科学家涂抹上化学药剂的蛹。
1. What is meant by "death chemical" mentioned in paragraph 3?
A A chemical that contains poison. B A chemical that causes death.
C A chemical that announces death. D A chemical that prevents death.
2. Which of the following is closest in meaning to the question "What keeps ants from hauling away the living dead? (paragraph 4)"?
A How do ants know what is to be hauled away from the dead ants?
B What prevents ants from removing the ants that are not yet dead?
C What do ants do to keep themselves away from the dying ants?
D What prevents ants from being carried away after they die.
3. What is NOT true about Choe's finding?
A When an ant dies, it produces a "I am dead" signal.
B Living ants have the death chemical on their bodies.
C Ants have two sets of chemicals on theft bodies.
D Ants have the "I am not dead" chemical on their bodies.
4. According to Choe's hypothesis,
A an ant still smells like a living when it dies.
B the "I am dead" chemical leaves the ant's body when it dies.
C the "I am not dead yet" chemical is left when an ant dies.
D the "I am not dead yet" chemical leaves the ant's body when it dies.
5. What is the result of the test on Choe's hypothesis?
A It proves that his hypothesis is time.
B Not enough evidence has been found to support his hypothesis.
C It shows that his hypothesis is wrong.
D It indicates that his hypothesis needs revising.
1. C 根据文章第二段和第三段的表述，阿根廷蚂蚁身上有种化学物质，它会告诉其他蚂 蚁“I am dead.”。文章没有说这种物质有毒，也没有说它能导致或预防死亡，所以其 他三项都是错误的选择。
2. B keep sb. from doing sth. 这个句型的意思是：使……不做……，阻止……去
做……。所以只有 B 是正确理解。
3. A 第三段和第四段告诉我们，蚂蚁身上会带有两种化学气味，“I am not dead yet” 和“I am dead”。这层意思分别在 B、C 和 D 中的表述出现。短文的第六段告诉我们， 蚂蚁死去时 ，“I am not dead yet”的气味就离开了它的躯体，剩下的就是“I am dead” 的 气味 。“I am dead”的气味不是死后新产生的化学物质。所以 A 是正确的选择。
4. D 短文第六段告诉我们，当“I am not dead yet”化学物质离开蚂蚁的躯体，“I'm dead” is left。这里，be left 的意思是：留了下来。所以，其他选项都是错误理解。
5. A 最后一段告诉我们，Choe 和他的研究小组用阿根廷蚂蚁蛹进行实验，结果与他的假 设吻合，即证实了他的假设。