posted by tim .
What are the adverbs in the sentence.
Long trips aboard these ships seemed highly improbable then.
Which two adverbs do you find?
these, highly, improbable and then
You're half right. :-)
The adverbs are "highly" which modifies the adjective "improbable," and "then," which modifies the verb, "seemed."
The other two are adjectives: "these" modifies "ships," and "improbable" modifies "trips."