_____have you worked in the factory?- For ten years.A.How long B.How often C.How many D.How old

问题描述:

_____have you worked in the factory?- For ten years.A.How long B.How often C.How many D.How old
但不知道什么理由

A
因为答语是一段时间,题目中又是用的现在完成时,因此用特殊疑问词how long,表示多长时间
how long 往往跟完成时连用
how often 是问频率的
how many 是问多少的
how old 是问岁数的