He is really good _______ English.
A. in B. on C. at D. with
In this sentence, the correct preposition to use is “at.” We use “at” to describe someone’s level of proficiency or ability in a particular subject or activity. For example, “He is really good at playing the guitar” or “She is really good at math.”
Difference Between “In,” “On,” and “At”
Preposition Usage Example in used to indicate a location within a larger space or a general time period “She lives in New York City.” or “I usually work in the morning.” on used to indicate a surface or a specific date or day “The book is on the table.” or “My birthday is on December 12th.” at used to indicate a specific point in time or a specific location “I will meet you at 3 PM.” or “I am at the airport.”