They arrived London the morning of July 1st.A. in; inB. on; inC. in; onD. at; on

问题补充：

They arrived London the morning of July 1st.

A. in; in

B. on; in

C. in; on

D. at; on

答案：

A. in; in

B. on; in

(答案→)C. in; on

D. at; on

解析：arrive at +小地点，arrive +in+大地点，在具体的一天的前面用介词on ，故选C