------_____ have you been swimming?-------Two hours A.When B.Where C.How long D.How many

题目

------_____ have you been swimming?-------Two hours A.When B.Where C.How long D.How many
选什么,为什么,

答案

------（C.How long） have you been swimming?-------Two hours.
你游了多久了?游了两小时.
how long用于对一段时间提问.