Jim was not（ ）his maths teacher's explanation of the problem, for he was still puzzled about it.
A、aware of
B、positive about
C、impressed by
D、content with
【正确答案】：D
【题目解析】：本题考查词组辨析。aware of：意识到，知道；positive about：对...积极，确信；impressed by：留下深刻印象；content with：满足于。句意：吉姆不满足于数学老师对这个问题的解释，因为他仍然对这个问题感到困惑。故D选项符合题意。
