这题看了前面这么多牛人的讨论,很有收获,我觉得首先 情态动词can应该尽量保留,其次,正如6楼说的, in fact 与possibly 是有点逻辑上的错误, 还有我个人 觉得it 应该是指代前面的整个 动作,used by the male for attracting females rise and fall in accordance with the surrounding temperature,
还有 我个人 觉得最好的选项 应该是 把e中的possibly去掉, serving作伴随 to attract females rises and falls in accordance with the surrounding temperature, in fact serving
LS虽然解释了一下,可是我觉得it指代the number of chirps,那么后面的serving就是修饰它的谓语falls and rises的,共同的主语就是the number of chirps。表达的意思是,因为number上升或是下降这种情况可以近似看成是一个温度计。表示伴随状态,前面整句话对后面的影响。