Judging from his face there was a confident smile, we knew that he didn’t lose heart.
A. in which
B. from which
C. by which
D. on which
网友回答
A. in which
B. from which
C. by which
(答案→)D. on which
解析：句意：从他带着自信的笑容的脸上，我们知道他没有灰心。这里使用了定语从句，先行词是his face，定语从句中缺少的是on the face，所以用on which引导定语从句，选D。