The trouble is that he really likes doing it but he' s______to admit it.
【正确答案】 C
【答案解析】shameful:可耻的,不体面的;shamed是动词shame的过去式(或过去分词);ashamed:惭愧的,感到难为情的;shaming:可耻的,令人羞愧的。根据句意可知,选C。