一道完成时的小选择题~
问题描述：
一道完成时的小选择题~
a number of fuctions【 】to the computer since it was first invented in 1946
问题是为什么选择have been added而不是用have been adding呢?他不是仍旧在添加,要用现在完成进行时么?表示动作持续?
答
a number of fuctions【 】to the computer since it was first invented in 1946问题是为什么选择have been added而不是用have been adding呢?他不是仍旧在添加,要用现在完成进行时么?表示动作持续?答：have been a...