Putting a cash value on the ecological services provided by nature—such as the water filtration “service” provided by a forested watershed—has, historically, been a (i)_____ process. Early attempts at such valuation resulted in impressive but (ii)_____ figures that were seized on by environmental advocates and then, when these figures were later (iii)_____, they were used by opponents to tar the whole idea.
答案：B,E,H