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.
- Rani ran across the lane.
- It took them several minutes to drive across the street.
- 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.
- We walked along the beach for a long time.
- Gichu hurried along the road towards us.
- 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.
- Ammu saw the car driving past the house.
- Mani arrived at half past eleven.
- Go past the yellow line, then turn let. You will reach the post.
- 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.
- The bus goes through a tunnel.
- Lechu walked through the doorway into the kitchen.
- It is not difficult to see through your plan. Anyone can see your motive.