October 15 th is my birthday I will never forget.A. whenB. thatC. whatD. which

问题补充：

October 15 th is my birthday, I will never forget.

A. when

B. that

C. what

D. which

答案：

A. when

B. that

C. what

(答案→)D. which

解析：句意：10月15日是我的生日，我将永远不会忘记的。which引导非限制性定语从句，在从句中做forget的宾语，非限定从中不能用that引导，故选D