Cambridge path 4

Before / As the Aztecs built Mexico City, there was a swamp there.

5. They ran up the beach after / as the waves came in, so they didn't get wet!

4. We had a fantastic time sightseeing after / when we went on vacation.

1. Before / When the land is dry, food can't grow.

3. Before / After they built the canal, it was much easier to travel from coast to coast.