TOEFL Mini-test (Skills 1-12)

“Of” correctly connects the noun “benefit” with “study.” It shows a relationship between the two nouns. Other options either introduce clauses unnecessarily or do not fit the structure. Prepositional phrases are essential for linking related ideas clearly.

“That” introduces a noun clause after “suggest.” This is standard in formal English. Other options do not correctly link the clause or create grammatical errors in sentence structure.

“That it” introduces a noun clause after “mean.” This structure completes the sentence logically. Other options are either incomplete or introduce incorrect connectors, making the sentence grammatically incorrect.

“Because” correctly shows cause. The incomplete data explains why the conclusion was delayed. Other options express contrast or transition, which do not match the intended meaning.

“With amphetamines can” correctly completes the comparison structure. It maintains parallelism and provides both subject and auxiliary verb. Other options either lack structure or introduce unnecessary connectors, making the sentence unclear or grammatically incorrect.

“That Wolf” introduces a relative clause modifying “concepts.” It correctly links the noun to the descriptive clause. Other options either lack connectors or create logical confusion. Relative clauses are essential for adding descriptive detail in complex sentences.

The sentence requires a subject before the verb “loom.” “The Santa Catalina mountains” correctly provides a plural subject that agrees with the verb. Other options either introduce unnecessary connectors or incorrect verb structures, making them incomplete or grammatically incorrect in forming a proper sentence.

“It had been” provides both subject and auxiliary verb required after “when.” The sentence needs a complete clause. Other options either add unnecessary connectors or omit the subject, making them incomplete.

“Becomes” correctly matches the subject “substance” and expresses a general truth in present tense. Other options use incorrect verb forms that do not fit the sentence structure or tense.

“Although” introduces contrast, which fits the sentence meaning. It shows that despite success, further testing is needed. Other connectors do not convey this contrast appropriately, making them incorrect.

“Dating” is a gerund functioning as a subject. The sentence already contains a main verb “provides,” so another verb form like “dates” would create conflict. The gerund correctly acts as a noun, forming a complete and grammatically correct sentence.

“What appears” functions as a noun clause acting as the subject. This structure is required because the sentence needs a subject before the verb. Other options either create incomplete clauses or incorrect sentence flow.

“Genes are” forms a complete subject and verb structure. The sentence requires a main clause, and other options introduce unnecessary connectors or incomplete ideas. This option correctly establishes the subject performing the action in a clear grammatical structure.

“As the commercial industry has” correctly follows the connector “inasmuch as.” It provides a subject and verb that logically complete the clause. Other options disrupt sentence flow or create incorrect structure.

“Follow” is correct because after “insisted that,” the subjunctive form is required. The base verb is used instead of a conjugated form. Other options incorrectly apply tense or form.