Notice that the ‘s’ on a regular verb shows that it is singular and agrees with a singular verb. This is rather confusing for international students; ‘s’ on a noun usually shows that it is plural [e.g. chair (singular); chairs (plural)]. So keep your wits about you—whether you are a native speaker of English or not.”
“C’mon, Mr. Lund; let’s move this along. This is way too easy.”
“Glad to hear that, Felix. Here you go. You do the next one.”
The price on the two blue shirts (is/are) too high.
“That’s easy. It’s ‘are’ because the subject is plural.”
“Whoa. Now, just hold your horses a minute, pardner. Did you say the subject was plural?”
“Yeah. Two shirts. That’s plural.”
“Do you agree, Kristy?”
“No, sir. ‘Two shirts’ is not the subject—because that is part of the prepositional phrase ‘on the two shirts.’ We learned that any words that are part of a prepositional phrase cannot be the subject of the sentence.”
“Look, Felix baby—let me help you here: cross out the prepositional phrase in that sentence.”
on the two blue shirts(is/are) too high.
“Okay, NOW tell me what is the subject of the sentence?”
“’Price.’ Now I get it. ‘Price’ is singular, so the verb should be ‘is.’”
“That’s the stuff!! Way to go, Mr. Happy-man!”
(Lesson interrupted here.)