Every possible means ______ to prevent the air pollution, but the sky is still not clear.
At the meeting they discussed three different _____ to the study of maths.
The bald eagle_____ the United States.
It was difficult to guess what her _____ to the news would be.
—How do you _____ to her unkindly behavior? —Only silence. Which of the following is wrong?
If his parents are convinced ______ the fact that his son always focuses his mind _______his study.