I tried hard . . . . . . . . impress my teacher. A. to B. from C. on D. at

The correct answer is: to.

The preposition “to” is used to indicate a goal or purpose. In this case, the speaker is trying to achieve the goal of impressing their teacher.

The other options are not correct because they do not indicate a goal or purpose.

• The preposition “from” is used to indicate a source or origin. In this case, the speaker is not trying to impress their teacher from a particular source.
• The preposition “on” is used to indicate a surface or location. In this case, the speaker is not trying to impress their teacher on a particular surface.
• The preposition “at” is used to indicate a time or place. In this case, the speaker is not trying to impress their teacher at a particular time or place.