By the time summer was gone, the ice was down to about 7.2m square kilometres.

而当那年夏季结束时，冰层减至到约720万平方公里。

There's definitely a time factor involved in the existence of ghosts, like certain flowers of spring that are gone by summer.

鬼的存在的确有时间性的，好像春天有的花，到夏天就没有。