—Oh, ________ air is so bad. Shall I open the windows to let in ________ fresh air?—Ok, thank you.
You should apologize _____ your mother _____ your rudeness.
People say that Vancouver is Canada’s most beautiful city, ______by mountains and the Pacific Ocean.
—Obviously, the boss looks happy again, doesn’t he? —Yes. It’s said that he has ______ the difficult problem.
A concert will be held in our city _____ the great musician.
We must do whatever we can _____ the river _____ any more.