96.
In some species of cricket, the number of chirps per minute used by the male for attracting females rise and fall in accordance with the surrounding temperature, and they can in fact serve as an approximate thermometer. (A) for attracting females rise and fall in accordance with the surrounding temperature, and they can in fact serve (B) for attracting females rises and falls in accordance with the surrounding temperature, which can in fact serve (C) in attracting females rise and fall in accordance with the surrounding temperature, in fact possibly serving (D) to attract females rises and falls in accordance with the surrounding temperature, and it can in fact serve (E) to attract females rises and falls in accordance with the surrounding temperature, in fact possibly serving
答案是D 但是 这个答案 中的It 指代什么呢，是the number of chirps 吗，如果是，把the number of chirps 代入句中，变成the number of chirps can in fact serve.....,进一步简化：the number can in fact serve.....,意思好像有点别扭，请NN指教。 | 
