A ____ is sweeping the floor.
A. cleaning
B. clean
C. cleaner
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He is cleaning his ____.
A. teeth
B. tooth
C. tooths
He is putting on his ____.
A. trouser
B. trousers
C. trouserses
These ____ are cooking a meal in the kitchen.
A. cooker
B. cook
C. cooks
The keyboard operators are typing ____ on the computers.
A. letters
B. letter
C. a letter