He was supposed to be there at seven, but he was running behind. In the hurry to evacuate, his laptop was left behind.
Yes, "behind" is a preposition that indicates the location or position of something in relation to another object or point.
After is a preposition of time, usually. "My sister was born after me." Behind is a preposition (or adverb) of place. "Our house was behind the airport." (preposition); "The children walked behind." (adverb).
He fell behind during the hike.
No, it is a proposition.
It's a preposition.
Early
"Behind" can be used as a preposition, an adverb, or an adjective, depending on its context in a sentence.
There is no adverb in this sentence. "Muddy" is an adjective, which modifies a noun. The only verb, "left" is unmodified. If you said, "We quietly left our muddy shows outside," then "quietly" would be an adverb, modifying the verb "left."
In the sentence "She looked behind," "behind" functions as a preposition indicating the location where she looked.
Adverb
to stay behind or to be left