At present，there is little doubt short message plays an increasingly important role in our lives．
A. whether
B. if
C. that
D. which
网友回答
A. whether
B. if
(答案→)C. that
D. which
解析：考查doubt用法. there is no doubt that 否定就用thatthere is doubt whether/if 肯定就用whether/if，说明有疑问,后接同位语从句。Little表达否定意思很少的,故选C.