68. We can learn from the passage that ants are ____________.
- A. not willing to share food
- B. not found around the poles
- C. more successful than all other animals
- D. too many to achieve any level of organization
答案：B
答案句：They also live nearly everywhere, except on frozen mountain tops and around the poles.
参考译文：它们也几乎生活在所有地方，除了冰冻的山顶和两极附近。
定位线索：题干“from the passage”→答案句取自第1段“They also live nearly everywhere, except on frozen mountain tops and around the poles.”；文中“except on frozen mountain tops and around the poles”对应选项B“not found around the poles”。
解析：题干问从文章能了解到蚂蚁怎么样。答案句直接说明蚂蚁几乎无处不在，除了冰冻山顶和两极附近，因此可推出蚂蚁在两极附近找不到，对应B选项。A选项“不愿分享食物”在文中无依据，属于无中生有；C选项“比所有其他动物更成功”程度过重，原文只说“astonishingly successful”，并未说超过所有动物；D选项“太多以至于无法实现任何组织水平”与原文矛盾，原文强调它们有很好的社会组织。
69. Ants can use pheromones for ____________.
- A. escape
- B. communication
- C. warning enemies
- D. arranging labor
答案：B
答案句：Where we use sound and sight to communicate, ants depend primarily on pheromone (外激素), chemicals sent out by individuals and smelled or tasted by fellow members of their colony.
参考译文：我们用声音和视觉交流，而蚂蚁主要依赖外激素——个体释放、被群体同伴闻到或尝到的化学物质。
定位线索：题干“use pheromones for”→答案句取自第2段“Where we use sound and sight to communicate, ants depend primarily on pheromone”；文中“communicate”对应选项B“communication”。
解析：题干问蚂蚁能用外激素做什么。答案句将蚂蚁的外激素与人类的交流方式（声音和视觉）类比，说明外激素用于交流，对应B选项。A选项“逃跑”、C选项“警告敌人”、D选项“安排劳动”在文中虽有提及外激素用于警告（alarm pheromone），但那是警告同伴而非敌人，且“arranging labor”并非外激素的功能，均不符合题意。
70. What does the underlined expression “take on” in Paragraph 3 mean?
- A. Accept.
- B. Employ.
- C. Play with.
- D. Fight against.
答案：D
答案句：They are completely fearless and will readily take on a creature much larger than themselves, attacking in large groups and overcoming their target.
参考译文：它们完全无所畏惧，会轻易地攻击比自己大得多的生物，成群进攻并战胜目标。
定位线索：题干“take on”→答案句取自第3段“They are completely fearless and will readily take on a creature much larger than themselves”；文中“attacking in large groups and overcoming their target”对应选项D“Fight against”。
解析：题干要求猜测“take on”在文中的含义。答案句中“take on”的宾语是“a creature much larger than themselves”，后文“attacking in large groups and overcoming their target”表明它们是在攻击并战胜目标，因此“take on”意为“对抗、迎战”，对应D选项。A选项“接受”、B选项“雇佣”、C选项“玩耍”均与后文的攻击行为不符。
71. Which of the following contributes most to the survival of ants?
- A. Their behavior.
- B. Their size.
- C. Their number.
- D. Their weight.
答案：A
答案句：For animals their size, ants have been astonishingly successful, largely due to their wonderful social behavior. … Behaving in this selfless and devoted manner, these little creatures have survived on Earth for more than 140 million years, far longer than dinosaurs.
参考译文：就它们这个体型的动物而言，蚂蚁取得了惊人的成功，很大程度上归功于它们出色的社会行为。……以这种无私和奉献的方式行事，这些小生物在地球上存活了超过1.4亿年，远比恐龙长久。
定位线索：题干“contributes most to the survival of ants”→答案句取自第1段“largely due to their wonderful social behavior”和第4段“Behaving in this selfless and devoted manner”；文中“social behavior”和“Behaving”对应选项A“Their behavior”。
解析：题干问哪个因素对蚂蚁的生存贡献最大。第1段明确指出蚂蚁的成功“largely due to their wonderful social behavior”，第4段又强调“Behaving in this selfless and devoted manner”使它们存活了1.4亿年，因此行为是主要因素，对应A选项。B选项“体型”、C选项“数量”、D选项“重量”在文中虽有提及，但都不是生存的主要原因，属于答非所问。