EXPLANATION If there is only one noun or pronoun in the subject of a sentence, it is easy to see what verb to use with it. If the sample sentence were simply The price (has/have) risen, everyone would insert has to agree with the noun price: The price has risen.
If we add, say, an adjectival phrase to qualify the noun price, the subject now has two nouns in it: The price of eggs... Some people might be tempted to change the verb from has to have to agree with the plural noun eggs. However, the subject is still price. (It is the price that has risen, not the eggs.) You will see how the phrase of eggs is adjectival if you study the following similar sentences. In all of them, price is the noun that the verb refers to.
- The price of milk has risen.
- The price of petrol has risen.
- The price of cars has risen.
When we use the word subject, we are usually referring to the complete subject of a sentence, that is the head word and other qualifying information, the complete noun phrase (for example, The price of eggs), but when we are discussing the agreement of subject and verb, we have the simple subject in mind - that is, the main noun in the phrase, the head word without any other information. When a simple subject is surrounded by other information, it is easy to lose sight of what the simple subject is. Here are some longer examples where the (simple) subject has been separated from the verb.
- The governments of the region agree that carbon pollution should be reduced.
- A variety of different foods is recommended as good for your health.
- Each of these paintings is by an Australian artist.
- The effort that the girls put into all the matches was commended by the coach.