Lucy decided a new computer.A. buyB. to buyC. buyingD. bought

问题补充：

Lucy decided a new computer.

A. buy

B. to buy

C. buying

D. bought

答案：

A. buy

(答案→)B. to buy

C. buying

D. bought

解析：句意：Lucy决定去买台新电脑。Decide to do sth.决定做某事，后接动词不定式，故选B。