4. The system according to claim 3 , wherein the system also comprises: a polyphonic word database and a phoneticizing unit; and wherein the memory further storing instructions that upon execution by the processor cause the system to: store Chinese character(s) and a marked Pinyin corresponding to the Chinese character(s); query the polyphonic word database to acquire the marked Pinyin corresponding to the input Chinese character when the number of the primary recommended word(s) is less than a preset threshold value; query again the recommended word database according to the Pinyin mark to acquire extended Chinese character(s) corresponding to the Pinyin mark; query the search tree storage unit according to the extended Chinese character(s) to acquire address information of extended recommended word(s) with the extended Chinese character(s) as a prefix; and query the recommended word database according to the address information of the mentioned extended recommended word(s) to acquire the extended recommended word(s) and then suggest the extended recommended word(s) to a user.
4. The system according to claim 3 , wherein the system also comprises: a polyphonic word database and a phoneticizing unit; and wherein the memory further storing instructions that upon execution by the processor cause the system to: store Chinese character(s) and a marked Pinyin corresponding to the Chinese character(s); query the polyphonic word database to acquire the marked Pinyin corresponding to the input Chinese character when the number of the primary recommended word(s) is less than a preset threshold value; query again the recommended word database according to the Pinyin mark to acquire extended Chinese character(s) corresponding to the Pinyin mark; query the search tree storage unit according to the extended Chinese character(s) to acquire address information of extended recommended word(s) with the extended Chinese character(s) as a prefix; and query the recommended word database according to the address information of the mentioned extended recommended word(s) to acquire the extended recommended word(s) and then suggest the extended recommended word(s) to a user. 5. The system according to claim 4 , wherein a combination of Pinyin is used to correspond to Chinese phrases containing polyphone in the polyphonic word database.