An ________ boy, Li Wen, works hard and gets good grades in his final exam.
eighteen-year-olds
eighteen-year-old
eighteen years old
Scott found_________ difficult to solve the problem.
She asked her teacher_________.
Don’t ________ away the dirty coat before________ me a clean one.
—Eric, no talking in class! —Sorry, I _______ next time.
The man sat ________ the bus, because he is the driver.