问题补充：
In the past few years，My Heart Will Go On was a popular song among young people, were often heard singing it at parties.
A. who
B. which
C. they
D. that
答案：
(答案→)A. who
B. which
C. they
D. that
解析：本题考查一个非限制性定语从句，先行词是young people,在从句中作主语。句意为“过去几年里，《我心永恒》这首歌在年轻人中间很流行，经常听他们(指年轻人)在晚会上唱它”。
