Complete the sentence with the correct form of the verb in brackets. Foreground the recent activity shown by present evidence: The caretaker's sleeves are wet and smell of soap because she ___ the stairwell. (clean)

الشرح

Has been cleaning is required because the wet, soapy sleeves are present evidence of recent activity. Has cleaned would focus on a finished stairwell rather than explaining the visible side effect on the caretaker.