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This "along" and "alongside" will drive me crazy, because examples are just the opposite of what we are taught.
On the Cambridge dictionary, I have seen the sentence:
I have been studying "along" and "alongside", and I have learnt that thin, long places like road, rivers, paths, beaches etc should be followed by "along" because it means "towards the end of something long in a line".
So, in the above sentence, we understand that pedestrian pathways are being built, which means that the pathways should start from the start of the road, in parallel to the road, and continue until the end of it, which perfectly requires the preposition "along". But why does the sentence have "alongside" and not "along"?