His grades are not as satisfactory as Jim.

His grades are not as satisfactory as Jim.
【正确答案】：His grades are not as satisfactory as Jim’s.
【题目解析】：as...as...意为”跟......一样“，比较的是不同人的同一种东西；根据前面主语是his grades，说明后面说的应该是Jim的分数，Jim's名词所有格表示”Jim的分数“，可省略grades。