Have you sent thank-you notes to the relatives from _ _ you received gifts?
A. which
B. them
C. that
D. whom
网友回答
A. which
B. them
C. that
(答案→)D. whom
解析：本题考查定语从句，首先从前后两个句子的谓语判断该空为关系代词，所以排除B，前面有介词from，排除C，又根据receive sth. from sb.，看出后面从句成分不完整，所以该句为定语从句，介词后面用whom指人，而which 指物，所以答案为D。