The man wearing what he likes was caught shortly.
We met a group of pupils returning from where they come from.
The man being happy is my brother.
第一和第二是对的吧，第三系动词是不可以做后置定语，是个错句吧？
The man wearing what he likes was caught shortly.
这个目前分词短语作定语，语法形式是正确的，但从表意上看是在说废话，听话人还是不了解此人穿了什么衣服，这个定语的意义何在？所以定语是多余的，应该删去。
We met a group of pupils returning from where they come from.
这个分词作定语，表面形式正确，但逻辑混乱。从他们来的地方返回？这是逻辑错误。句子第一要表达一个逻辑意义，不是为了造句而说话。
The man being happy is my brother.
系词be的目前分词不能作定语，所以这是错句。改为the happy man。
