How many times ____ you ____(see) films when you were in Beijing?

题目

How many times ____ you ____(see) films when you were in Beijing?
为什么

答案

have ...seen
此句翻译为：你在北京的时候看过几次电影?
此句是when引导的时间状语从句,如果从句用过去式,那么主句用现在完成时