-Do you know in Ya’an? On the 20th of April .A. how many people died in the ear

问题补充：

---Do you know in Ya’an? --- On the 20th of April，.

A. how many people died in the earthquake

B. how many days the earthquake lasted

C. when the earthquake happened

D. when did the people die

答案：

A. how many people died in the earthquake

B. how many days the earthquake lasted

(答案→)C. when the earthquake happened

D. when did the people die

解析：句意：你知道雅安地震是什么时候发生的吗？4月20日。答语是时间，应该选择由when 引导的宾语从句，要用陈述语气。故选C。