No comma before or after a preposition

One of the most common grammatical errors on the ACT English Test and, to a slightly lesser extent, the SAT Writing Test is the use of a comma before or after a preposition (a time or location word). Common prepositions: Of, To, For, From, In, On, By, Between, About, With, Around, Across, Through, Over, Under This construction is virtually always incorrect, and any answer that contains it should automatically be eliminated. Note that even if the original version in the passage doesn’t contain it, one or more of the other answers might include it. Incorrect: The gentle rustling of leaves in the breeze, the crunch of twigs underfoot, and the eclectic mix of birdsong are the sounds one typically expects to hear while walking, through the forest. Incorrect: The gentle rustling of leaves in the breeze, the crunch of twigs underfoot, and the eclectic mix of birdsong are the sounds one typically expects to hear while walking through, the forest. Correct: The gentle rustling of leaves in the breeze, the crunch of twigs underfoot, and the eclectic mix of birdsong are the sounds one typically expects to hear while walking through the forest. Many wrong answers on ACT English involve this error; you can very often get down to two answers and occasionally down to one just by crossing options that contain it.