they almost always outweigh the expense of planting and maintaining trees.
但是，它们几乎总大于树木的种植和维护的费用 。
For example, one five-city study found that, on a per tree basis, cities accrued benefits ranging from roughly $1.50 to $3.00 for every dollar invested.
所以可能需要长达5年的时间才能从所种植的树木上获得利益,例如能源节约效益的见 效。
After 15 years, an average tree usually has matured enough to provide the full range of benefits.
生长15年后，平均每棵树就已经成熟到足够提供全方位的利益了。
ppt课文讲解
姓名：李流迪 班级：城市规划09 指导老师：何江
单词
take effect 见效;生效 mature [mə‘tjuə] 成熟的;酿熟的 considerably [kən’sidərəbli]相当,非常,颇 outweigh胜过，比...更重，比...更重要 maintain [mein‘tein]维修,保养 invest [in'vest]投(资)[(+in)]
In all five cities, the benefits outweighed the costs, as shown in Figure 9. nk you
In calculating benefits, it is important to note that trees grow slowly,
在计算利益的时候，必须注意到树木的生长是很缓慢的，
so it may take as long as five years for some benefits from trees , such as energy savings, to take effect.
Oh！co1m5yeeaorsn ！ Mom，I’Im’m velrayters…tr…ong scared！ now！
Although the benefits can vary considerably by community and tree species,
虽然所获得的利益会因为群落和树种的不同有很大的差别
例如，一项对5个城市的研究发现，在每棵树的基础上，城市 能从投资的每一美金上获得1.50到3.00美元的利益。
These cities spent about $15-65 annually per tree, with net benefits ranging from approximately $30-90 per tree. 这些城市每年在每棵树上花费大约15-65美元，每棵 树所带来的净效益约为30-90美元不等。