All of the nouns used (hammer, chain, furnace, brain, anvil) are explaining mighty things that the tiger is being compared to. The poem is simply saying that they are smart, speedy, and strong.
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~Travis
It depends on which word is underlined.
If the underlined word is <em>boat, </em>then it is used as A. predicate nominative in this sentence.
A predicate nominative is a noun following a copulative/linking verb.
The linking verb in this sentence is <em>is, </em>and the noun following it is <em>boat. </em>
16-17 antonyms 18-19 synonym 20 antonyms