【题目】As the smallest child of his family, Alex is always longing for the time _______ he should be able to be independent.
A.which
B.where
C.whom
D.when

【答案】D
【解析】句意：作为家里最小的孩子，Alex 总是渴望他能够有独立的时间。这里使用定语从句，先行词是 the time,定语从句中缺少时间状语，用关系副词when,所以选D.