The _________ look on her face suggested she _________ the _________ maths problem．A.puzzled; be puzzled by; puzzlingB.puzzling; was puzzled by; puzzledC.puzzled; was puzzling over; puzzlingD.puzzling; be puzzled over; puzzled
网友回答
C解析puzzled多叙述人的感受。puzzle over表示“苦思”；puzzling，表示“让人感到困惑的”。