4. [20 points] The following grammar in BNF is a small excerpt from the English grammar (what each variable stands for is written in parenthesis on the left of each production): (sentence) (noun phrase) (verb phrase) (prepositional phrase) == | :== | | :== ::== (adjective) == time (article) ::== an (noun) == arrow | flies | time == like ::== like | time (preposition) (verb) Using the sentence "time flies like an arrow" show that the English language is ambiguous. Write your derivation similar to the following format (use only left derivations): time