A: The top 25% of the city, such as Chinese A, is the top 25% of all candidates in the senior high school entrance examination. B: It accounts for 30% of the city. For example, Math B is the top 30% of all senior high school entrance examination candidates. C: It accounts for 20% of the city. For example, English C means that the score is in the top 20% of all senior high school entrance examination candidates.