Arabic is a Southern-Central Semitic language that is spoken as the official language of 22 countries, known as the Arab world. Arabic has many spoken dialects. However, Modern Standard Arabic is the form of Arabic that is taught in schools and used in the media. Arabic has 29 letters (28 if "hamzah" is not counted as a letter) that represent consonants and long vowels. Short vowels are represented by diacritical marks.
Chinese refers to a family of languages (known as "the Sinitic languages"). The most widely spoken languages of this family are Mandarin, Wu, Yue, Min, and Jin (with more than 40 million speakers in each). The difference between these languages is mainly in pronunciation and vocabulary. The sound system of Chinese is marked by the use of tones, which differentiate the meanings of words that have the same sounds.
Russian is an East Slavic language of the Indo-European family. It is spoken in Russia and the countries of the former Soviet Union by about 280 million speakers. The Russian alphabet is based on the Cyrillic alphabet and consists of 33 letters.