They considered a puter, which was considered a great help in their work.
A. to buy；to be
B. buying；being
C. to buy；being
D. buying；to be
网友回答
A. to buy；to be
B. buying；being
C. to buy；being
(答案→)D. buying；to be
解析：句意：他们考虑买一台计算机，被认为是在其工作中有很大的帮助。consider vt1.考虑，+v-ing 2. 把(某人、某事)看作…，认为(某人、某事)如何〔后接 as ..., of ..., (to be) ... 等〕,根据题意可知D正确。
考点: 考查非谓语动词的用法辨析。