Which of the following statement is true about Chinese calligraphy? ( )
选项：

A:Since calligraphy uses Chinese characters as its vehicle of expression, one has to know Chinese language to appreciate its beauty.
B:Brush pens have been used to practise and improve people's handwriting for thousands of years.
C:It is very easy to appraise a calligraphic work.
D:A brush, paper, ink stick and a table are commonly referred to as the “four treasures of the study”.