给定一个字符串，要求判断它是否能由其它两个字符串合并而成。当两个字符串合并成 一个新的字符串时，新串的字符顺序必须与原串中的顺序相一致。 -Given a string of requirements to determine whether it can be incorporated by the other two strings together. When the two strings are combined into When a new string, string n