Line 4: “Keel” has multiple meanings. The first is the part of the ship that goes along the underside that gives the ship stability in the water. This usage really doesn’t make much sense, though, because one can’t see a “steady keel” unless the boat has fallen over. The other use of keel here is as a synecdoche. The keel, a part of a boat, is used to represent the whole boat. More importantly, "the steady keel" lets us know that, despite its rough trip, the ship (like the nation) remains steadfast and true.
https://www.shmoop.com/o-captain-my-captain/ship-symbol.html
Answer:
Protagonists and antagonists are both essential characters in a story, but they propel the plot in different and usually opposite ways: ... In storytelling terms, this means that protagonists and antagonists are opposing forces in a story.
Explanation:
First of all, it is important to define preposition phrase in order to find it in this sentence. We can say that "<span>a prepositional phrase will begin with a </span>preposition<span> and will end with a </span>noun<span>, </span>pronoun<span>, </span>gerund<span>, or </span>clause<span>, the "object" of the preposition"
</span>
*In this case, we find UNTIL TODAY as the only prepositional phrase presented. until is the preposition and today is the noun.