51. What is the distinctive feature of a sea slug?
- A. It looks like both a plant and animal.
- B. It lives half on animals and half on plants.
- C. It converts some sea animals into plants.
- D. It gets energy from both food and sunlight.
答案：D
答案句：Well, those dividing lines come crashing down with the discovery of a sea slug(海姑蛹）that's truly half animal and half plant. It's pretty incredible how it has managed to hijack the genes of the algae (藻类）on which it feeds. … The slugs can manufacture chlorophyll, the green pigment (色素）in plants that captures energy from sunlight, and hold these genes within their body. … And so far, this green sea slug is the only known animal that can be truly considered solar-powered, although some animals do exhibit some plant-like behaviors.
参考译文：然而，随着一种真正半动物半植物的海蛞蝓的发现，这些分界线崩塌了。它设法劫持了它所食用的藻类的基因，这相当令人难以置信。……这些海蛞蝓能够制造叶绿素——植物中捕获阳光能量的绿色色素，并将这些基因保存在体内。……到目前为止，这种绿色海蛞蝓是已知唯一一种真正可以被视为太阳能驱动的动物，尽管有些动物确实表现出一些类似植物的行为。
定位线索：题干“distinctive feature”→答案句“truly half animal and half plant”及“solar-powered”；文中“hijack the genes of the algae”、“manufacture chlorophyll”、“captures energy from sunlight”对应选项D“gets energy from both food and sunlight”。
解析：题干问海蛞蝓的显著特征。答案句指出它“半动物半植物”，能劫持藻类基因制造叶绿素并利用阳光能量，同时它本身也吃藻类（从食物获取能量），因此D“从食物和阳光中获取能量”正确。A“看起来像植物和动物”是字面误解，文中强调功能而非外观；B“一半靠动物一半靠植物”偷换概念，文中指基因来源；C“把一些海洋动物变成植物”无中生有。
52. What enables the sea slug to live like a plant?
- A. The genes it captures from the sea plant algae.
- B. The nutrients it hijacks from other species.
- C. The mechanism by which it conserves energy.
- D. The green pigment it inherits from its ancestors.
答案：A
答案句：The slugs can manufacture chlorophyll, the green pigment (色素）in plants that captures energy from sunlight, and hold these genes within their body. … In fact, the slugs use the genetic material so well that they pass it on to their future generations .
参考译文：这些海蛞蝓能够制造叶绿素——植物中捕获阳光能量的绿色色素，并将这些基因保存在体内。……事实上，海蛞蝓利用这些遗传物质如此之好，以至于它们将其传递给后代。
定位线索：题干“live like a plant”→答案句“manufacture chlorophyll”、“captures energy from sunlight”；文中“hold these genes”、“use the genetic material”对应选项A“The genes it captures from the sea plant algae”。
解析：题干问什么使海蛞蝓能像植物一样生活。答案句明确说海蛞蝓能制造叶绿素并持有从藻类劫持的基因，从而利用阳光能量，因此A“从海藻中捕获的基因”正确。B“从其他物种劫持的营养”偷换概念，文中是基因而非营养；C“节约能量的机制”无中生有；D“从祖先继承的绿色色素”错误，文中说基因来自藻类，且后代需吃藻类才能获得。