为什么jog、play 等要用现在分词的形式?

问题描述:

为什么jog、play 等要用现在分词的形式?
People respectively choose jogging,playing basketball,swimming,skating,climbing or riding as their regular exercises

他们在句子中做动名词用.
人们分别选择慢跑,打篮球,游泳,溜冰,爬山或者骑车作为他们的常规锻炼.