GreenOG P364
※加粗部分是每段的point，第二段划线部分有两个对比结构（最近看语法看得比较敏感。。。），括号部分用来抽离主干让句子结构更清晰，当然只是我个人的看法，不对的地方望大家指正
Biologists have advanced two theories to explain why schooling of fish occurs in so many fish species. Becauseschooling is particularly widespread among species of small fish, both theoriesassume that schooling offers the advantage of some protection from predators.
生物学家们提出了两种理论来解释为何鱼群中通常都包含很多不同种类的鱼。鉴于成群结队的行为尤其出现在很多种类的小鱼中，这两个理论都假设成群结队地行动能保护他们免受捕食者的攻击。
Proponents of theory A dispute the assumptionthat a school of thousands of fish is highly visible. Experiments have shownthat any fish can be seen, even in very clear water, only within a sphere of200 meters in diameter. When fish are in a compact group, the spheres ofvisibility overlap. Thus the chance (of apredator (finding the school)) is only slightly greater than the chance (of the predator (finding a single fish swimming alone)).Schooling is advantageous to the individual fish because a predator's chance (offinding any particular fish swimming in the school) is much smaller thanits chance (of finding at least one of the same group of fish (if the fish weredispersed throughout an area)).
理论一的支持者反驳了这样一个假设：拥有上千条鱼的鱼群非常显眼。实验证明，即使在非常清澈的水里，任何一条鱼都只能在直径为200米的范围内被看见。当鱼紧凑地组成鱼群时，他们的能见范围就会发生重叠。那么捕食者发现鱼群的几率也只比发现单只鱼的几率大一点点。因为捕食者发现鱼群中某一条鱼的几率远远小于当鱼散布在某一水域时至少发现同一群鱼的几率，所以结伴而行对鱼是有好处的。
However, critics of theory A point out thatsome fish form schools even in areas (where predators are abundant) and thuslittle possibility of escaping detection exists. They argue that the schoolcontinues to be of value to its members even after detection. They advocatetheory B, the "confusion effect", which can beexplained in two different ways.
然而，对于理论一存在着这样一种质疑：有些鱼即使在天敌丰富的水域里也聚群行动，于是他们在面对天敌时逃离的可能性就很小。质疑者认为即使鱼群被天敌发现后，结伴而行也还是对鱼有不小的价值。他们倡导理论二——“混淆效应”，这种理论可以从两个不同的方面来解释。
Sometimes, proponents argue, predators simply cannot decide which fish to attack which fish to attack. This indecision supposedly results froma predator's preference for striking prey that is distinct from the rest of theschool in appearance. In many schools the fish are almost identical inappearance, making it difficult for a predator to select one. The secondexplanation for the "confusion effect" has to do with the sensory confusion caused by a large number of prey moving aroundthe predator. Even if the predator makes the decision to attack a particularfish, the movement of other prey in the school can be distracting. Thepredator's difficulty can be compared to that of a tennis player trying to hit atennis ball when two are approaching
simultaneously.
理论二的支持者们认为，捕食者就是单纯的不知道该选择攻击哪一条鱼。这种犹豫不决恐怕是因为捕食者更偏向于捕食一群鱼中外形最与众不同的那条。在很多鱼群中，鱼的外形几乎一模一样，这使得捕食者难以在他们中选择一个攻击对象。另一个关于“混淆效应”的解释与感官的混淆有关，这种混淆主要是由大量的鱼在捕食者周围游动造成的。即使捕食者决定了要攻击哪一条特定的鱼，鱼群中其他鱼的游动也会让它分心。捕食者的这种处境就好像是一个网球运动员在面临两个同时靠近的球不知道该选择打哪个一样。
PIE结构：
第一段：
Point：有两个理论来解释为啥一群鱼里会出现很多不同种类的鱼
Illustrate：俩理论假设结伴而行可以保护鱼不受捕食者攻击
第二段：
Point：理论一认为捕食者发现鱼群的几率只比发现单只鱼的纪律大一点点
Illustrate：聚群时鱼的能见范围会发生重叠，藏在鱼群中更加不容易被捕食者发现
第三段：
Point：理论二为“混淆效应”
Illustrate：理论二对理论一提出了一个质疑：一群鱼当碰到捕食者时很难逃跑
第四段：（从两个方面解释理论二）
Point 1：当面临一群鱼时捕食者不知道选择哪一条
Illustrate 1：很多鱼群里的鱼几乎都一模一样个，捕食者不知道选哪个，就选了长得最与众不同的那条
Point 2 ：一群鱼容易给捕食者造成感官上的混淆
Illustrate 2：一群鱼在捕食者周围游动容易让捕食者分心
Example：就比如一个网球运动员，两颗球同时靠近时他就不知道该选择哪个了