她在粗糙的人行道上擦伤了膝盖。

She ___scratched her knee on the rough sidewalk.

他不小心用钥匙划伤了桌子。

He accidentally ___scratched the table with his keys.

孩子们经常在学校课桌上刻他们的首字母。

Children often ___scratch their initials on school desks.