1. An English input method, comprising: receiving an input English character string having an original length; calculating a target length based on the original length of the English character string; looking up a target English word having a length between the original length and the target length; calculating a longest common length between the target English word and the English character string, where the common length refers to a length of identical letters; and returning the target English word when the longest common length is equal to N times the target length, where N is a positive number less than or equal to 1.