.---Who is the perfect person _______ the new president?---Mr White. We all thought he should be the most suitable choice while _______ together.
If there are ______ trees, the air in our city will be _______ cleaner.
You shouldn't ____ the boy's mistakes.
______our teacher is ill, ______ he still comes to our class to teach us.
The teacher said that the earth ______ around the sun.
I felt it hard to keep up with my classmates. But whenever I want to__ __,my teacher always encourages me to work harder.