这里为何是attending to?focus on跟哪个并列？

Children experiencing these disorders find it difficult to screen out unimportant information, and focus on everything in the environmentrather than attending to a single activity.

请问

rather than后面为何是attending to不是attend to?感觉它跟focus on是并列的。还是说attending to是跟experiencing是并列的？

focus on是跟find并列吗？

rather than既能够用作准并列连词，也可以是复合介词。这里用作复合介词，后接动名词结构。你应该知道这种使用方法，而不要拘泥于准并列连词使用方法。

rather than attending to a single activity修饰的是focus on...。