OG11 Purple: 36不明白到底是什么意思

36. Two decades after the Emerald River Dam was built, none of the eight fish species native to the Emerald River was still reproducing adequately in the river below the dam．Since the dam reduced the annual range of water temperature in the river below the dam from50 degrees to 6 degrees, scientists have hypothesized that sharply rising water temperatures must be involved in signaling the native species to begin the reproductive cycle．

Which of the following statements，if true，would most strengthen the scientists’ hypothesis?

(A)  The native fish species were still able to reproduce only in side streams of the river below the dam where the annual temperature range remains approximately 50degrees．

(B)  Before the dam was built，the Emerald
      River annually overflowed its banks，creating    backwaters that were critical breeding areas for the native species of fish．

(C)  The lowest recorded temperature of the Emerald
      River before the dam was built was 34 degrees，whereas the lowest recorded temperature of the river after the dam was built has been 43 degrees．

(D)  Nonnative species of fish，introduced into the Emerald
      River after the dam was built, have begun competing with the declining native fish species for food and space.

(E)  Five of the fish species native to the Emerald
     River are not native to any other river in North America．

突然觉得意思无法理解。

在Emerald River Dam 建成后，河中原来的8种原住民fish没有一种足够的繁殖。因为大坝使得河水温度每年的范围从50度降低到6度。科学家预言说，迅速上升的温度一定是河里原来的物种开始从新繁殖的信号。

A.说的是本土鱼类只能在大坝下面水流中繁殖，此时年温度范围保持在50度。

我的问题是：河水的温度范围从50度到6度，说明河水的温度几乎保持不变。因为温度范围=Tmax-Tmin;当温度范围是50度，说明最高温度比最低温度高50度。当温度范围是6度，说明最高与最低温度差别是6度。所以河水温度上升。所以科学家说温度上升表示水中鱼类开始从新繁殖。但是A说的是鱼类只能在温度范围为50度的水丽繁殖...如此说来，当温度升高时，鱼类应该不能繁殖才对...这样不是strengthen科学家的预言啊？

。。。。求解。。。

Which of the following statements，if true，would most strengthen the scientists’ hypothesis?

(A)  The native fish species were still able to reproduce only in side streams of the river below the dam where the annual temperature range remains approximately 50degrees．

(B)  Before the dam was built，the Emerald
      River annually overflowed its banks，creating    backwaters that were critical breeding areas for the native species of fish．

(C)  The lowest recorded temperature of the Emerald
      River before the dam was built was 34 degrees，whereas the lowest recorded temperature of the river after the dam was built has been 43 degrees．

(D)  Nonnative species of fish，introduced into the Emerald
      River after the dam was built, have begun competing with the declining native fish species for food and space.

(E)  Five of the fish species native to the Emerald
     River are not native to any other river in North America．

突然觉得意思无法理解。

在Emerald River Dam 建成后，河中原来的8种原住民fish没有一种足够的繁殖。因为大坝使得河水温度每年的范围从50度降低到6度。科学家预言说，迅速上升的温度一定是河里原来的物种开始从新繁殖的信号。

A.说的是本土鱼类只能在大坝下面水流中繁殖，此时年温度范围保持在50度。

我的问题是：河水的温度范围从50度到6度，说明河水的温度几乎保持不变。因为温度范围=Tmax-Tmin;当温度范围是50度，说明最高温度比最低温度高50度。当温度范围是6度，说明最高与最低温度差别是6度。所以河水温度上升。所以科学家说温度上升表示水中鱼类开始从新繁殖。但是A说的是鱼类只能在温度范围为50度的水丽繁殖...如此说来，当温度升高时，鱼类应该不能繁殖才对...这样不是strengthen科学家的预言啊？

。。。。求解。。。

我选D 如果D 对的话我是这样理解的  原文说鱼减少是因为水温降低，但D 给出他因  是因为与外来鱼竞争而减少  从而削弱了原推理依据

看到题目上说的是 the dam reduced the annual range of water temperature  from50 degrees to 6 degrees

这里dam减少的不是range吗？怎么是of后面的temperature啊？