This sentence uses the gerund "approaching" when the noun "approach" already exists. Changing "approaching" to "approach" clarifies the sentence. The corrected sentence reads, "It can be difficult to hear the approach of cars running on electric engines."

The timeline of verb tenses in this sentence doesn’t quite make sense. Read it out loud and you will probably hear that something is wrong. Since the first half is in the past, the second half should be too. The corrected sentence reads: After attending a workshop on cake decorating, Joe has brought edible works of art to every family gathering.

The correct verb tense would be "make," since the sentence is phrased as a question and is not a declarative statement about something in the past.

This sentence has a problem with the timeline of verb tenses. Since the first half of the sentence is in the past, the second half has to be too. The corrected sentence reads, "As soon as I bought an expensive patio umbrella I found them on clearance everywhere."

This sentence has a problem with verb tenses. Since the first half of the sentence is in the past, the second half has to be too. The corrected sentence reads, "They puzzled over the little mysteries of life and language, wondering if it was possible to mingle in a group of two."

The timeline of this sentence isn’t quite right. Read it out loud, and you will probably hear that something is funny with the verb tense. Since the first half is in the past, the second half has to acknowledge that. The corrected sentence reads: Since he finally quit his stressful job, Joe has been full of energy and witty banter.

This sentence does not maintain a logical timeline between verb tenses. Read it out loud, and it will probably sound funny. “Had never encountered” should be used following a sentence in the past, not the present. The corrected sentence reads: Harold almost never complains, but he has never encountered customer service this lousy before.

This sentence uses the incorrect tense of the verb “to be.” The corrected sentence reads: Scientists debate whether the primary reason for the extinction of the prehistoric wooly mammoth was overhunting by humans or climate change.

This sentence uses the wrong verb tense. “Had been giving” is clunky and unnecessary. The corrected sentence reads: Bob agonized over the logic puzzle that Charlie had given him, and Charlie took delight in his agony.

This sentence uses the wrong form of the verb “to be.” “Was” is a better choice than “being” in this case. The corrected sentence reads: George was desperately excited to go caroling through the snow, but unfortunately it was July and he would have to wait.