A typical (36) language contains an applicative sub-language which approximates the mathematical abstractions of "timeless" functions applied to’ "spaceless" values, where the actual operation sequences and use of storage space during expression evaluation are organized behind the (37) . In this setting, values are data structures of low volume, typically a few computer words or less, which means that an illusion of spacelessness can be realized by having (38) results during expression evaluation stored at the discretion of the language implementation, and effecting parameter (39) and (40) operations through value copying.

40（）

A. foreground

B. background

C. screen

D. scenes

委托销售企业代理方式的主要优点，是企业可以充分利用市场经济造就的卖方市场优势，对销售方即物流的执行方进行选择和提出要求，有利于实现企业理想的供应物流设计。（）