ou'd better _______all the lights are off before you go to bed.

A．look through

B．find out

C．take care

D．make sure

城镇体系组织结构的材料出口模式主要出现在( )。

A．新开发区

B．资源丰富而经济落后的国家或地区

C．内陆地区

D．沿海地区