he is doing some shopping.请问shopping前面为何要加一个some做什么呀,

he is doing some shopping.请问shopping前面为何要加一个some做什么呀, It is sunday .Helen"mother ( )doing some shopping. My mom is doing some shopping in the m___ He went shopping() some food . "doing some shopping "有没有错? the best place to do some shopping is ...to do做什么结构? 关于 do some doing 的词语.例如 ：do some shopping 可以说do some shopping,请问可以说do shopping吗? Tom is doing some shopping in the supermarket now.(对doing so do some shopping和does some shopping go shopping 和do some shopping有什么不同 do some shopping