—How is your pet dog? — He is lovely. But if he _______ at home all day, he _______ at me angrily.
The students went out of the classroom _____ .
Do you have other _____ to make on the subject?
Bob doesn’t know _____ to write about.
We must be strict _____ ourselves and strict _____ our work.
Now more and more people prefer__to__in order to reduce the air pollution.