同学你好，该知识点来自沪江网校《【Uni智能】雅思语法精讲【随到随学班】》的课程，想要更系统的学习，欢迎进入课程学习。不仅可以和更多的同学一起学习，而且还有老师、助教随时的学习指导和知识点解答哦。

同学你好呀。

1. 现在完成时has/have done一般有以下几种情况：

a) 表示过去开始并持续到现在的动作。
China has changed a great deal in the past 20 years.

b) 强调过去动作对现在的影响和结果。
Where have you put the dictionary? I can't find it anywhere.

c) 表示反复性或习惯性。常常与often, frequently及表示次数之类的词连用。
I have watched him appear on TV several times.

2. 现在完成进行时have been doing:

a) 表示过去某时开始的动作一直持续到现在，并在持续期间内不断进行着。
I have been working for five years.

b) 表示重复的动作。
Jim has been ringing John every night for the last week.

希望有所帮助喔～