TOEFL Mini-test (Skills 27-29)

“Occurs” is correct because the subject “a complex system” is singular, even though the sentence begins with a prepositional phrase. Inversion places the verb before the subject, but agreement still follows the subject. Singular subjects require singular verbs, making “occurs” the correct choice in this structure.

“Homes” is correct because the verb “have” requires a plural subject. The sentence already contains a verb, so only the subject is needed. Singular options with verbs create grammatical errors. Proper subject-verb agreement ensures clarity and correctness in sentence construction.

“Are” is incorrect because the subject “each number” is singular and requires a singular verb “is.” Words like “each” always take singular verbs. Using a plural verb creates disagreement, which is a common grammatical error in English.

“Is trying” is incorrect because the subject “scientists” is plural and requires the plural verb “are trying.” Subject-verb agreement must match number. Using a singular verb with a plural subject creates inconsistency and grammatical error.

“Are” is incorrect because the subject “a hotel” is singular. Even though the sentence begins with a prepositional phrase, the verb must agree with the true subject. The correct verb should be “is.” Understanding inversion helps identify the correct subject.

“Has” is incorrect because the subject “advances” is plural and requires “have.” Subject-verb agreement depends on the main noun, not nearby words. Using a singular verb with a plural subject creates a mismatch.

“Involve” is incorrect because the subject “one” is singular, even though it refers to a group. Therefore, the correct verb should be “involves.” Expressions like “one of” always take singular verbs, making this a common agreement rule.

“Was” is incorrect because “laws” is plural and requires “were.” Subject-verb agreement must match the number of the subject. Using a singular verb with a plural noun creates grammatical inconsistency.

“Are” is incorrect because the subject “a majority vote” is singular. Therefore, the verb should be “is.” Even when phrases appear complex, identifying the true subject ensures correct agreement and sentence accuracy.

“Is” is incorrect because the subject “ideas” is plural. The correct verb should be “are.” Sentences beginning with “there is/are” must agree with the noun that follows. Proper agreement ensures clarity and correctness in structure.