In general, larger moths can fly faster than smaller ones and hence have a better chance of evading flying predators, but they also have higher optimal body temperatures, which explains why ______.
文章前面表示大的蛾会比小的飞的快并且牠们能有较佳机会逃离predators,
黄色部份是我觉得最重要的, 这句说但牠们也须有高的optimal body temperatures这个前提假设下