[解析]
(1)推理判断题。根据第二段中He showed pity to someone who was hurting,and had kind words,and offered to help in any way he could.(他对受到伤害的人表示同情,说了一些善意的话,并表示愿意尽他所能提供帮助)可知,Joe很善良,乐于帮助别人。故选C。
(2)细节理解题。根据第三段中An experiment began when I went to the supermarket.I smiled as I went up and down the supermarket and people I didn't even know smiled back at me.(当我去超市时,一项实验开始了。我微笑着在超市里走来走去,甚至我不认识的人也对我微笑)可知,作者的实验是在超市里对别人微笑。故选A。
(3)推理判断题。根据最后一段中Now I know a smile is a small thing,but what if we all tried to smile a few more times each day?I couldn't believe how great I felt.Nothing in my life had changed,but maybe it had.What I had learned was that such a small thing could lift not only my spirits,but also the spirits of those around me.So smile!(现在我知道微笑是一件小事,但是如果我们都试着每天多笑几次呢?我简直不敢相信自己感觉有多好。我的生活没有任何改变,但也许改变了。我学到的是,这样一件小事不仅可以振奋我的精神,也可以鼓舞我周围的人。所以微笑吧!)可推知,作者的实验非常令人满意。故选D。