Someone complaining about life often can never experience the real happiness of lifecomplaining用动词ing为什么用about不用of?

Someone complaining about life often can never experience the real happiness of life
complaining用动词ing
为什么用about不用of?

这里的complain是抱怨的意思,所以用about,如果是诉说的意思就用of.
complaining about life 这是定语,用来修饰someone的,中间省略掉了who is,完整的句子是someone who is complaining about.
这句话意思是：经常对生活有抱怨的人绝不会体会到生活的真正乐趣.