Prepositions by Themselves Can Function as Adverbs
When their objects are understood, prepositions
often function as adverbs. In the sentence, "Come in." it is understood
that the speaker is inside something -- a room, a house, a den -- so the
object of "in" is left out. In such cases, you can usually consider the
preposition by itself to be an adverb.
1. Put parentheses ( ) around each prepositional phrase.
2. Underline subjects once, finite verbs twice, and label complements ("PN," "PA," IO," "DO").
3. Draw an arrow from each preposition (without an object) to the word it modifies.
Mama Skunk was worried because she could never keep track of her
two children. They were named In and Out, and whenever In was in, Out
was out; and if Out was in, In was out. One day she called Out in to her
and told him to go out and bring In in. So Out went out and in no time at
all he brought In in.
"Wonderful!" said Mama Skunk. "How, in all that great forest, could
you find him in so short a time?"
"It was easy," said Out. "In stinct."
--This Week Magazine