Question

【题目】There is no doubt _______ scientific knowledge is very important for teenagers.
A.whether
B.that
C.if
D.what

Answer 1

【答案】B
【解析】句意：毫无疑问，科学知识对于青少年来说很重要。whether是否；that引导宾语从句无意义，只起连接作用；if是否；what什么。句型：There is no doubt that……毫无疑问……。所以答案是B。