By the time Mr.Jackson arrived in Shanghai,he___many famous cities in Europe.
问题描述：
By the time Mr.Jackson arrived in Shanghai,he___many famous cities in Europe.
选has visited 还是had visited?
答
用had visited,填过去完成时.
根据句意,杰克逊先生到达上海已经发生在过去（因为用的arrived一般过去时）,但在那时,他已经去过欧洲的很多城市了,这发生在过去的过去,所以要再往前推一个时间点,用过去完成时.