—When did you uncle arrive China? — He got to Guangzhou the morning of April 16th.A. at;

问题补充：

—When did you uncle arrive China?

— He got to Guangzhou the morning of April 16th.

A. at; in B. in; in C. in; on

答案：

解析：句意:你叔叔什么时候到的中国？他在4月16日的早晨到的广州。arrive in+大地点，arrive at+小小地点，中国属于大地方，所以用in，在具体某一天的早晨应该用on。故选C。