他们在森林里四处走著，纯粹只是好玩。
这是由于人口的增加会降低人均费用份额的事实，但同时增加的交通挤塞，由于城市森林是不是纯粹的公共物品。
This is due to the fact that population increase would reduce the share of the cost per capita, but at the same time increase the congestion since urban forests are not purely public goods.
其中有些纯粹是礁石的岛，有些则布满了绿色的森林，其中很多岛上有小村庄和村舍，它欢迎着大家去钓鱼、游泳、和露营。
Some are just rocks; others are green with forests. Many have small villages and country homes. Everyone is welcome to fish, swim and camp.
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