有一读者问这样一句话：
(1)Professor Lin left yesterday for America where a lecture tour has been arranged for him.
这里，where从句里用的是现在完成时has been arranged，而不是过去完成时，理由何在？
是的，过去完成时是可以用的。不过，两相比较，还是用现在完成时较好，因为：现在完成时和现在（即说话人的说话时间）有关，意味着“讲学”正在进行，如用过去完成时，则与现在无关； 现在完成时用在这里，所表示的时间与现在比较贴近，如用过去完成时， 就会使人觉得远离现在了。
现在完成时所表的时间先于过去一般时的现象，在英语中还是比较常见的，这里再举一些例子如下：
(2)I felt lost in the city today. I have been away too long.
(3)I have just heard a most extraordinary piece of news, and I had to come to tell you all about it.
(4)She has made several attempts to get away, but we succeeded in persuading her to stay.
(5)Mother, this will come as a surprise to you, but I have met a girl here in San Francisco and we were married yesterday.
其实，在日常生活中，如：
(6)I haven't seen you for ages.
(7)I have missed you so.
(8)Have you waited long?
像这样的句子，从时间上讲，也都是发生在before I saw you之前， 只不过这个过去一般时未表现出罢了。
