directly to the sun in summer will do great harm to our skin.A. Be exposedB. Being expose

问题补充：

directly to the sun in summer will do great harm to our skin.

A. Be exposed

B. Being exposed

C. Exposing

D. Exposed

答案：

A. Be exposed

(答案→)B. Being exposed

C. Exposing

D. Exposed

解析：非谓语动词辨析。动名词短语做主语且需用被动结构。意为：夏天被直接暴露在太阳下会对我们皮肤有害。