Often he sit for hours doing nothing at all when he was in low spirits.A. shouldB. wouldC.

问题补充：

Often he sit for hours doing nothing at all when he was in low spirits.

A. should

B. would

C. could

D. might

答案：

A. should

(答案→)B. would

C. could

D. might

解析：本题考查情态动词。此处would相当于used to，表示过去的习惯动作。