__________ my return, I heard that my parents ___________ at the supermarket．
A.At；wentB.On；have beenC.On；had beenD.During；had been在线课程C
“on +表示动作意义的名词／动名词”形式，意为“一……就……”；主句为过去时，宾语从句动作发生在主句之前，从句应用过去完成时.答案为C.