一、单项选择（每小题1分，共15分）
( )1. - How does she open the box?
- She opens the box _______ a knife.
A use B. on C. with D. by
( )2. We all know it's useful _______English well.
A to learn B. learn C. learning D. for learning
( )3. After they go _______ the tunnel, they will go _______ the street.
A. through; across B. across; down
C. into; on D. up; down
