【题目】Adolescence is the period of life ______ youths leave childhood and head into adulthood, which is a difficult physical and emotional process.
A.whenB.whereC.thatD.which
在线课程【答案】A
【解析】
考查定语从句。句意：青春期是青少年离开童年走向成年的人生阶段，这是一个艰难的身体和情感过程。本句为定语从句，先行词是the period of life，指时间，从句中缺少状语，用when引导。故选A。