送交者: mangolasi 于 2006-1-10, 06:36:15:
回答: 说说为什么早晨和晚上空气好 由 疫苗 于 2006-1-10, 04:21:41:
Photosynthesis takes place only in the daytime. But the trees are breathing 24-hour. I guess the fresh oxygen is at lowest level in the morning if the trees are consuming oxygen in a constant rate.