一个英语句子的成分ing形式和to do形式到底应该怎么用呢?

问题描述:

一个英语句子的成分ing形式和to do形式到底应该怎么用呢?
两个句子,后面有的接ing,有的接to do,能拜托解释下为什么用不同的形式?
1 Now researchers suspect that dreams are part of the mind's emotional thermostat,regulating moods while the brain is "off-line"
2 And one leading authority says that these intensely powerful mental events can be not only harnessed but actually brought under conscious control,to help us sleep and feel better

意思不一样啊.第一个regulating moods while the brain is "off-line"是dreams的同位动作.起到了定语的作用.
第二个to help us sleep and feel better则是解释intensely powerful mental events的作用的.