I smoke out of habit not for pleasure; for I have been in the habit for twenty years.A.

问题补充：

I smoke out of habit, not for pleasure; for I have been in the habit for twenty years.

A. a; the

B. the; a

C. x; the

D. x; x

答案：

A. a; the

B. the; a

C. x; the

(答案→)D. x; x

解析：该题考查冠词的用法。out of habit＝by habit是固定短语，意为“出于习惯，潜意识地”。for pleasure意为“为享乐，为消遣”，也是固定短语。