Nobody knew who was the first at school that morning when the window was broken.A. arriv

问题补充：

Nobody knew who was the first at school that morning when the window was broken.

A. arriving

B. arrived

C. to arrive

D. have arrived

答案：

A. arriving

B. arrived

(答案→)C. to arrive

D. have arrived

解析：the first to do sth ，表示第一个做…事的人，故选C