Every Friday is the school open day parents can go to the class to observe it .A. where

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。