A、Because it is the earliest English textbook. B、Because it indicates the high standard of print quality at that time. C、Because

An almost 100-year-old English textbook might be the earliest such book published in China, its owner, Mr. Wang, told reporters last week in Beijing.
    The 440-page textbook, entitled "English with Chinese Phonetics", was possibly published in 1904 or before, predating another early textbook, "English Words at Entrance Level", which was thought to be the earliest English textbook in China.
    Though almost a century old, with pages yellow with age, the various letter types listed in the book are still clearly recognizable, displaying the high standard of print quality at that time. As the title of the book suggests, the textbook uses Chinese characters to provide phonetic equivalent for English words, thus constituting a major drawback of this early school tutorial work, since there was no such a thing as standardized Mandarin at that time, the phonetics were arranged in line with the so-called "orthodox" Cantonese, resulting in misleading and what today seems a quite funny effect. Nevertheless, the book has been hailed as a "revolutionary guidebook inventing creative study methods for those ambitious people doing foreign businesses".
    The book was acquired by its present owner, Mr. Wang, quite by chance. In 1992, when he was living in Papua New Guinea, an old local Chinese, originally from Guangdong Province presented him the book as a gift.