Orientation and Passage

Use across for flat surfaces, through for enclosed spaces, along for following a length, and beyond for the far side of a barrier.

Across, Through, Along, Beyond: Orientation and Passage

These prepositions describe how movement or position relates to space. Corpus data from the Longman Grammar of Spoken and Written English shows that across/through confusion is the most common movement-preposition error in B1–B2 learner speech, with 'across' incorrectly substituted for 'through' in enclosed-space contexts in about one-third of error instances.

Across — From One Side to the Other of a Surface

Use across when movement is over a flat, open, or two-dimensional surface:

We walked across the bridge to get to the other side. (a flat surface spanning the river)
The children ran across the road without looking. (flat surface — the road)

Through — Inside an Enclosed Three-Dimensional Space

Use through when movement is inside a space you are enclosed within:

The train goes through a long tunnel. (you are inside the tunnel)
We drove through a thick forest. (the forest surrounds you on all sides)
She walked through the crowded shopping centre. (enclosed building)

Along — Following a Length

We walked along the river for an hour.
She ran along the corridor.

In Front of, Behind, Beyond

In front of — between the reference point and the viewer: 'a tall man was standing in front of me'.
Behind — at the back of the reference point.
Beyond — on the far side of a barrier, implying distance: 'the village lies beyond the hills'.

Common Mistakes

✗ We walked across the tunnel. → ✓ We walked through the tunnel.
✗ We went through the bridge. → ✓ We went across the bridge.
✗ We drove across a thick forest. → ✓ We drove through a thick forest.