—What was wrong with you yesterday evening?

—I ________ my homework when the light went off suddenly. [ ]

A. doing

B. was doing

C. did

D. have done

在我国，以下的典故可以说是家喻户晓，广为传颂。其中不能直接体现中 * * 精神核心的是（）

A.愚公移山

B.屈原投江

C.苏武牧羊

D.岳母刺字