decide on + n/动名词结构
eg：he has decided on （going there）/（that trip）.
decide to do 不定式结构 （非谓语）
eg：he has decided to go for a holiday.
另外 decide on 强调决定了什么事（可决定做可决定不做）
eg：he has decided on the complex decision which troubled him for a long time.
decide to do 强调决定了要做某事
eg：he decided to refuse her .