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, it is required to determine whether the merger by the other two strings. When two strings into a new string, the string of characters in the new order must be the order of the original string is consistent.