Question

Ju Hua Tai is a popular song among young people, ___were often heard singing it in Karaoke.

1. A.
   which
2. B.
   who
3. C.
   that
4. D.
   what

Answer 1

B
考察定语从句。一旦判定为定语从句，就应该排除what ,又因为非限定性，所以排除that .因为先行词是young people 所以选who.