问题补充:
Every Friday is the school open day , parents can go to the class to observe it .
A. where
B. when
C. whose
D. which
答案:
A. where
(答案→)B. when
C. whose
D. which
解析: 考查定语从句。先行词是the school open day ,在定从 parents can go to the class to observe it中作时间状语,所以选B。