_____（do）eye exercises is good for your eyes.填什么?写清楚理由.（以do为原型）

楼上2位只说对了一半。
To do 和doing 都是可以的。
to do 不定式短语可以作主语，doing动名词短语也可以作主语。

Doing eye exercises is good for your eyes.
动名词doing eye exercises 作为主语

Doing eye exercises is good for your eyes
做眼保健操对眼睛有益.
动名词doing eye exercises 作为主语

Doing动名词