My visit to your school is really an unforgettable experience, I will treasure for ever.
A. that
B. one
C. it
D. what
网友回答
A. that
(答案→)B. one
C. it
D. what
解析：B 句意：我到你们学校的参观确实是一次令人难忘的经历。我将永远珍惜这样的经历。根据句意，此处应用one作an unforgettable experience的同位语，后面是省略that或者which的定语从句。