When I __ my breakfast,I shall ring her up.为什么用have had

问题描述:

When I __ my breakfast,I shall ring her up.为什么用have had

强调打电话之前,先完成吃早饭的动作.
如果只是have,则表示“当我一吃饭,我就给她打电话”.打电话和吃饭当然不能一起进行的了