_____ the window, my finger was cut unexpectedly. 
   A. Clean     B. To clean     C. While cleaning    D. While I was cleaning  

______ the window, my finger was cut unexpectedly.

A. While I was cleaning    B. To clean    C. Cleaning    D. While cleaning

_____the window,my finger was cut unexpectedly.

A.Cleaning   B.While cleaning   C.While I was cleaning   D.To clean

______ the window, my finger was cut unexpectedly.

A. While I was cleaning    B. To clean    C. Cleaning    D. While cleaning