Question

【题目】Our teacher is too busy. I'm not sure _______ he will come to the party or not.
A.when
B.that
C.until
D.whether

Answer 1

【答案】D
【解析】句意：我们老师太忙了，我不确定他是否会来参加聚会。when当……时；that只引导从句，无意义；until直到；whether是否，通常与or not连用构成固定搭配，所以答案是D。