Theory:

Across, along, past, and through denotes movement. They are prepositions of movement.
Across: Movement showing something going from one side to the other side of a place.
Example:
  1. Rani ran across the lane.
  2. It took them several minutes to drive across the street.
  3. The cat chased the mouse across the lawn.
Along: Movement showing something going in a constant direction on a road or a path, more or less in a horizontal line.
Example:
  1. We walked along the beach for a long time.
  2. Gichu hurried along the road towards us.
  3. We were not allowed to cross the frontier. So we drove along it as far as we could and came back happy.
Past: Movement showing something is going beyond something else.
Example:
  1. Ammu saw the car driving past the house.
  2. Mani arrived at half past eleven.
  3. Go past the yellow line, then turn let. You will reach the post.
  4. The horse went past the winning post and had to be stopped with difficulty.
Through: Movement showing something going into one side and out of the other side of an opening.
Example:
  1. The bus goes through a tunnel.
  2. Lechu walked through the doorway into the kitchen.
  3. It is not difficult to see through your plan. Anyone can see your motive.