As an ambulance approaches and passes you how can you explain the sound it produced

when an ambulance passes with its siren blaring, you hear the pitch of the siren. The siren's pitch sounds higher than when it is moving away from you.

So while the siren produces waves of constant frequency, as it approaches us

Explanation:

the sentence does not violate the phrase structure second rule (introduced by noam chomsky) because noun phrases consist of a determiner such as a, the or every, and a noun. in the sentence, the noun phrase the cake includes a determiner (the) and a noun (cake).

on the other hand, the first rule indicates that a sentence encloses a noun phrase, followed by a verb phrase. the example sentence can be analysed as follows:

john (n) + ate (v) + the (det) + cake (n).