Don’t lose your progress!

We cover every section of the GMAT with in-depth lessons, 5000+ practice questions and realistic practice tests.

Up to 90+ points GMAT score improvement guarantee

The best guarantee you’ll find

Our Premium and Ultimate plans guarantee up to 90+ points score increase or your money back.

Master each section of the test

Comprehensive GMAT prep

We cover every section of the GMAT with in-depth lessons, 5000+ practice questions and realistic practice tests.

Schedule-free studying

Learn on the go

Study whenever and wherever you want with our iOS and Android mobile apps.

The most effective way to study

Personalized GMAT prep, just for you!

Adaptive learning technology focuses on your academic weaknesses.

Sentence Correction: Tenses - Past Perfect

After massive military preparations for Operation Barbarossa, the Axis powers were poised to conquer the Soviet Union in the summer of 1941, but their defeat at the Battle of Moscow in December of that year reveals that they had not imagined the Red Army will mobilize troops from the vast Soviet territories.

Incorrect.

This answer choice is grammatically incorrect. The sentence uses the Present Simple tense reveals to describe an event that occurred at a specific moment in the past (the Battle of Moscow in December 1941). 

In addition, the second part of the sentence is anchored in the past by the Past Perfect verb had not imagined. By default, this sentence should remain in the Past tense. The verb will mobilize, however, is in the Future tense.

[[snippet]]

Incorrect.

While this answer choice corrects one of the original tense mistake, it repeats the other. Using the Present tense reveals to describe an event that occurred at a specific moment in the past (the Battle of Moscow in December 1941) is grammatically incorrect.

[[snippet]]

In addition this answer choice is stylistically flawed. Changing they didn't imagine to it hadn't been imagined makes the sentence ambiguous and confusing, as it is not clear who or what it refers to.

Incorrect.

While this answer choice corrects one of the original tense mistakes, it repeats the other.

The second part of the sentence is anchored in the past by the Past Perfect verb hadn't imagined. By default, this sentence should remain in the Past tense. The verb will mobilize, however, is in the Future tense.

[[snippet]]

Incorrect.

While this answer choice corrects both original tense mistakes, it is grammatically incorrect: it uses the Past Simple tense (did not imagine) to describe an action that was completed before another action in the past.

Since the Axis power's failure to imagine that the Soviet military would mobilize occurred before the Battle of Moscow revealed this failure, the Past Perfect tense should be used to describe the earlier action.

Excellent work!

This answer choice corrects both tense mistakes in the original question. It changes reveals in the Present to revealed in the Past Simple (to describe an action that occurred at a specific time in the past - December '41). It also changes will in the Future to would in the Future Past, as required by the verb had not imagined, which anchors the action in the past.

Note also that like the original sentence, this answer choice correctly uses the Past Perfect to describe an action that occurred before another action in the Past, as the Axis power's failure to imagine that the Soviet military would mobilize occurred before the Battle of Moscow revealed this failure.

reveals that they had not imagined the Red Army will mobilize troops from the vast Soviet territories
reveals it hadn't been imagined that the Red Army would mobilize troops from the vast Soviet territories
revealed that they hadn't imagined the Red Army will mobilize troops from the vast territories of the Soviet Union
revealed that they did not imagine that the Red Army would mobilize troops from the Soviet Union's vast territory
revealed that they had not imagined the Red Army would mobilize troops from the vast Soviet territories