receives an average of 30 inches of precipitation a year; transpiration from soil and from plants returns approximately 21 of the 30 inches to the atmosphere, while the balance of 9 inches contributes to the flow of streams and rivers.
(A) transpiration from soil and from plants returns approximately 21 of the 30 inches to the atmosphere, while the balance of 9 inches contributes to the flow (E) as transpiration from soil and from plants return approximately 21 of the 30 inches to the atmosphere, the rest of the 9 inches contribute to the flow
我不明白E。旧prep上讲是as表比较错误。但as不是可以引导时间状语从句吗？"当……的时候"。如 、As you grow older，you will grow wiser。 如果除去单复数问题，E能不能对呢？ 旧prep上的解释： 2) as的用法:as + n表示作为… , as +主语+谓语表示动作之间进行比较