【题目】Sales of CDs have declined dramatically since the early 2010s, when people ______ to enjoy music downloaded from the internet.
A. have begun. B. began. C. begin. D. would begin.
在线课程【答案】B
【解析】
考查动词时态。句意：自2010年代初以来，CD的销量急剧下降，当时人们开始享受从互联网下载的音乐。when引导的是定语从句，此处指the early 2010s发生的事，用一般过去时。故选B.