It is obvious that people hold different opinions about voluntary services should be financially rewarded.
A. that
B. what
C. how
D. whether
网友回答
A. that
B. what
C. how
(答案→)D. whether
解析：句意：很显然许多人持不同的观点对于志愿服务是否应该给予经济奖励。这里about后跟的宾语从句，空格后的句子是被动语态，所以不缺少主语和宾语，故排除AB;G根据句意故选D。