Read the sentence. The cost of the new bridge went beyond the previous estimate. Which part of the sentence is the adjectival phrase?

the cost of the new bridge

of the new bridge

went beyond the previous estimate

beyond the previous estimate

Your answer would be that the adjectival phrase is of the new bridge.

Explanation:

In the sentence above, the adjectival phrase is of the new bridge. This is a multiword adjective which is not headed by an adjective. The phrase is headed by the preposition of. However, this string of words acts as an adjective because it is modifying a noun, the NP the cost. That is why it can be considered an adjectival phrase.