Question

proofreading parallel structure - triathlons
read the passage and correct the the words that dont match the others in the list.
most athletes are always looking for a new challenge to test their limits and develop their skills. for many, triathlons offer the right mix of mental and physical training. in a triathlon, athletes compete in swimming, biking, and running, all in the same race.
beginners usually start with the sprint triathlon, in which athletes swim for one quarter of a mile, bike for ten miles, and run for five kilometers. for more serious competitors, there are other triathlons of varying lengths. the hardest and most extreme is the famous ironman triathlon, which requires racers to swim 2.5 miles, go biking 150 miles, and run an entire marathon, one right after the other.
success in this sport requires athletes not only to master the physical demands of the race but also training their minds as well. focus on the course and transitioning quickly from one part to another are crucial in achieving the lowest possible race time. the triathlon may be a difficult and demanding sport, but the feeling of accomplishment after finishing one is worth the effort.

Explanation:

1. In the parallel structure listing triathlon disciplines, "develop" is a base verb while the others are gerunds; it should match the gerund form.
2. In the Ironman task list, "go biking" is a phrasal verb phrase while the others are simple base verbs + distance; it should use the simple base verb form.
3. In the "not only...but also" structure, "to master" is an infinitive while "training" is a gerund; they need to match in form.
4. In the list of crucial skills, "Focus" is a noun/base verb while "transitioning" is a gerund; they need to match in gerund form.

Answer:

1. Change "develop" to developing (to match the gerund form of "looking" in the parallel phrase "looking for a new challenge to test their limits and developing their skills")
2. Change "go biking" to bike (to match the simple verb form of "swim" and "run" in the parallel list "swim 2.5 miles, bike 150 miles, and run an entire marathon")
3. Change "training" to to train (to match the infinitive form of "to master" in the "not only...but also" structure "not only to master the physical demands...but also to train their minds")
4. Change "Focus" to Focusing (to match the gerund form of "transitioning" in the parallel list "Focusing on the course and transitioning quickly from one part to another")

Revised key sentences:

• "Most athletes are always looking for a new challenge to test their limits and developing their skills."
• "The hardest and most extreme is the famous Ironman Triathlon, which requires racers to swim 2.5 miles, bike 150 miles, and run an entire marathon, one right after the other."
• "Success in this sport requires athletes not only to master the physical demands of the race but also to train their minds as well."
• "Focusing on the course and transitioning quickly from one part to another are crucial in achieving the lowest possible race time."