【题目】I told you that he would come to see you.
—Actually I had little doubt ________ it was true.
A.whether
B.that
C.since
D.if

【答案】B
【解析】doubt后面的同位语从句,如果主句是否定句或疑问句,则同位语从句用that引导,且that在从句中不做任何成分；如果主句是肯定句,则doubt后面的同位语从句用whether引导.
此题doubt前面有形容词little,表示否定,所以其后面的同位语从句只能用that引导.