--- Look! The paint is starting to come off _______ the wall is damp.

--- Well, we’d better have the wall repainted some day.[ ]

A. when

B. where

C. if

D. once

期货市场的作用有（）。

A．对资源配置起基础性作用

B．使企业回避或减轻风险

C．对生产经营和投资起导向作用

D．推动企业技术革新和采用新设备

E．起调节供求、稳定经济的作用