At the beginning of class, the noise of desks______could be heard outside the classroom.
As is known to all language learners, newly learnt words will soon be forgotten unless ______ used in everyday communication.
Judging from his face_______ there was a confident smile, we knew that he didn’t lose heart.
As the quality of the city’s air continues to give rise to ______, the residents are encouraged to set off fewer fireworks.
Tom’s score on the test is the highest in the class. He _____.
I’m afraid I’m not ________ to help with the talent show, for I am fully occupied with my own project.