Have you sent thank-you notes to the relatives from _ _ you received gifts?

问题描述:

Have you sent thank-you notes to the relatives from _ _ you received gifts?
Have you sent thank-you notes to the relatives from __ you received gifts?
为什么不填that ,填whom

因为这里需要指代的是 relatives,亲戚们
from 是要和 receive 连在一起理解