TOEFL Review Skill Quiz: Targeted Practice Test

1. _______ in the region dropped from forty thousand in 1980 to twelve thousand by 2005, alarming conservation authorities.

For a number of wildlife species

The number of wildlife species

When the number of wildlife species

That the number of wildlife species

"The number of wildlife species" correctly functions as the singular subject of the main verb "dropped." "For a number of wildlife species" is a prepositional phrase that cannot serve as a sentence subject. "When the number of wildlife species" introduces a subordinate time clause, leaving the sentence without a main clause. "That the number of wildlife species" creates a noun clause that would require a main clause verb to complete the sentence.

Explanation

"The number of wildlife species" correctly functions as the singular subject of the main verb "dropped." "For a number of wildlife species" is a prepositional phrase that cannot serve as a sentence subject. "When the number of wildlife species" introduces a subordinate time clause, leaving the sentence without a main clause. "That the number of wildlife species" creates a noun clause that would require a main clause verb to complete the sentence.

2. Because of her longstanding concerns about the proposed budget cuts, _______ declined to sign the departmental agreement.

Who

And

Which the director

The director

"The director" correctly serves as the subject of the main clause following the introductory prepositional phrase. "Who" is a relative pronoun that introduces a dependent clause and cannot function as a standalone main clause subject. "And" is a coordinating conjunction, not a noun phrase capable of acting as a subject. "Which the director" forms a broken relative clause with no main predicate to complete the sentence.

Explanation

"The director" correctly serves as the subject of the main clause following the introductory prepositional phrase. "Who" is a relative pronoun that introduces a dependent clause and cannot function as a standalone main clause subject. "And" is a coordinating conjunction, not a noun phrase capable of acting as a subject. "Which the director" forms a broken relative clause with no main predicate to complete the sentence.

3. Dolphins navigate through murky waters by _______ ultrasonic pulses and interpreting the returning signals.

The emission of

Emitted

Emitting

They emit

"Emitting" is the correct gerund form required after the preposition "by." A preposition must be followed by a noun or gerund, not a full clause. "The emission of" is a noun phrase that would require an object to complete it, making the sentence grammatically awkward in this structure. "Emitted" is a past participle that cannot follow a preposition in this construction. "They emit" is a full subject-verb clause, which cannot grammatically follow a preposition.

Explanation

"Emitting" is the correct gerund form required after the preposition "by." A preposition must be followed by a noun or gerund, not a full clause. "The emission of" is a noun phrase that would require an object to complete it, making the sentence grammatically awkward in this structure. "Emitted" is a past participle that cannot follow a preposition in this construction. "They emit" is a full subject-verb clause, which cannot grammatically follow a preposition.

4. It has been projected that unless agricultural output is significantly increased, _______ the growing global population.

So we will be unable to feed

And it cannot sustain

Which will not support

We will not be able to feed

"We will not be able to feed" correctly completes the conditional structure introduced by "unless," providing a full independent clause expressing the consequence. "So we will be unable to feed" uses a result connector that does not appropriately follow an "unless" conditional clause. "And it cannot sustain" uses a coordinating conjunction that creates a run-on rather than a conditional result. "Which will not support" is a relative clause that leaves the sentence without a main clause.

Explanation

"We will not be able to feed" correctly completes the conditional structure introduced by "unless," providing a full independent clause expressing the consequence. "So we will be unable to feed" uses a result connector that does not appropriately follow an "unless" conditional clause. "And it cannot sustain" uses a coordinating conjunction that creates a run-on rather than a conditional result. "Which will not support" is a relative clause that leaves the sentence without a main clause.

5. To calculate a structure's load capacity, the dimensions and material strength of the structure must be carefully measure.

Calculate

Dimensions

Carefully

Measure

"Measure" is incorrect and should be "measured." The sentence uses a passive construction — "must be measured" — which requires the past participle form of the verb. "Calculate" is correctly used as the base form in the infinitive phrase "to calculate." "Dimensions" correctly functions as part of the compound subject. "Carefully" correctly functions as an adverb modifying the past participle.

Explanation

"Measure" is incorrect and should be "measured." The sentence uses a passive construction — "must be measured" — which requires the past participle form of the verb. "Calculate" is correctly used as the base form in the infinitive phrase "to calculate." "Dimensions" correctly functions as part of the compound subject. "Carefully" correctly functions as an adverb modifying the past participle.

6. The most reliable method for archiving sensitive documents are through an encrypted cloud-based storage system.

Most reliable

For archiving

Are

Through

"Are" is incorrect and should be "is." The subject of the sentence is "the most reliable method," which is singular and requires the singular linking verb "is." "Most reliable" correctly functions as a superlative adjective modifying "method." "For archiving" correctly functions as a prepositional phrase specifying the purpose. "Through" correctly introduces the prepositional phrase describing the storage mechanism.

Explanation

"Are" is incorrect and should be "is." The subject of the sentence is "the most reliable method," which is singular and requires the singular linking verb "is." "Most reliable" correctly functions as a superlative adjective modifying "method." "For archiving" correctly functions as a prepositional phrase specifying the purpose. "Through" correctly introduces the prepositional phrase describing the storage mechanism.

7. The research institute has been collaborating with international universities actively since the past four years to address climate-related challenges.

Has been collaborating

International universities

Actively

Since

"Since" is incorrect and should be "for." "For" is used with a duration of time, as in "for the past four years," while "since" is used with a specific point in time such as "since 2020." "Has been collaborating" is correctly used as the present perfect continuous to describe an ongoing activity. "International universities" correctly functions as the object of the preposition "with." "Actively" correctly functions as an adverb modifying "collaborating."

Explanation

"Since" is incorrect and should be "for." "For" is used with a duration of time, as in "for the past four years," while "since" is used with a specific point in time such as "since 2020." "Has been collaborating" is correctly used as the present perfect continuous to describe an ongoing activity. "International universities" correctly functions as the object of the preposition "with." "Actively" correctly functions as an adverb modifying "collaborating."

8. When a municipality operate without a balanced budget, essential public services are the first to face funding reductions.

Operate

Balanced

Essential

Face

"Operate" is incorrect and should be "operates." The subject "a municipality" is singular and requires the third-person singular verb form "operates" in the subordinate time clause. "Balanced" correctly functions as an adjective modifying "budget." "Essential" correctly functions as an adjective modifying "public services." "Face" correctly agrees with the plural subject "essential public services."

Explanation

"Operate" is incorrect and should be "operates." The subject "a municipality" is singular and requires the third-person singular verb form "operates" in the subordinate time clause. "Balanced" correctly functions as an adjective modifying "budget." "Essential" correctly functions as an adjective modifying "public services." "Face" correctly agrees with the plural subject "essential public services."

9. The historian became widely recognized in academic circles as an authority on colonial trade routes after she spend decades researching primary sources.

Widely recognized

Academic circles

Authority on

Spend

"Spend" is incorrect and should be "spent." The sentence describes a completed past action — the historian spending decades on research — which requires the simple past form "spent." "Widely recognized" correctly functions as a passive adjectival phrase. "Academic circles" correctly functions as the object of the preposition "in." "Authority on" correctly functions as a noun phrase with its accompanying preposition.

Explanation

"Spend" is incorrect and should be "spent." The sentence describes a completed past action — the historian spending decades on research — which requires the simple past form "spent." "Widely recognized" correctly functions as a passive adjectival phrase. "Academic circles" correctly functions as the object of the preposition "in." "Authority on" correctly functions as a noun phrase with its accompanying preposition.

10. Inasmuch _______ the new environmental guidelines affect all registered manufacturers, compliance audits have been scheduled for the coming quarter.

That

Which

As

Of

"As" correctly completes the fixed conjunction "inasmuch as," meaning "to the extent that" or "because," used here to introduce the reason compliance audits were scheduled. "That" does not combine with "inasmuch" to form a recognized conjunction in standard English. "Which" is a relative pronoun and cannot complete this conjunction or introduce a reason clause. "Of" is a preposition and cannot link two full clauses in this grammatical structure.

Explanation

"As" correctly completes the fixed conjunction "inasmuch as," meaning "to the extent that" or "because," used here to introduce the reason compliance audits were scheduled. "That" does not combine with "inasmuch" to form a recognized conjunction in standard English. "Which" is a relative pronoun and cannot complete this conjunction or introduce a reason clause. "Of" is a preposition and cannot link two full clauses in this grammatical structure.

TOEFL Review Skill Quiz: Practice Skills 1 To 36

1. _______ in the region dropped from forty thousand in 1980 to twelve thousand by 2005, alarming conservation authorities.

2.

What first name or nickname would you like us to use?

2. Because of her longstanding concerns about the proposed budget cuts, _______ declined to sign the departmental agreement.

3. Dolphins navigate through murky waters by _______ ultrasonic pulses and interpreting the returning signals.

4. It has been projected that unless agricultural output is significantly increased, _______ the growing global population.

5. To calculate a structure's load capacity, the dimensions and material strength of the structure must be carefully measure.

6. The most reliable method for archiving sensitive documents are through an encrypted cloud-based storage system.

7. The research institute has been collaborating with international universities actively since the past four years to address climate-related challenges.

8. When a municipality operate without a balanced budget, essential public services are the first to face funding reductions.

9. The historian became widely recognized in academic circles as an authority on colonial trade routes after she spend decades researching primary sources.

10. Inasmuch _______ the new environmental guidelines affect all registered manufacturers, compliance audits have been scheduled for the coming quarter.