I want to know that you can distinguish between Chinese, Japanese, Korean?

I am English and cannot speak or understand any of the languages you mention but, as a bookseller and librarian, I know the difference between Chinese, Japanese and Korean scripts (but I can't answer your question above because MyLot does not allow non-Roman scripts). I will describe what I know. Chinese has a single, quite complex, character to represent each word. On the whole (in printed characters, at least) each character is a more or less square block. Traditionally, Chinese is written from top to bottom of the page and the first page of a book is on the right hand side, if it is held with the fore-edge facing one, so it is read in the reverse of the Western style book. Modern Chinese (in Newspapers and on websites) may, however, be printed in horizontal, left to right fashion. Japanese characters are much simpler and represent syllables, not words, though some Japanese texts may contain Chinese characters. Japanese is written and printed in horizontal lines reading left to right. The Korean script is very different. It is also a syllabic script but each syllable is built into a block representing the whole word. The syllables in each block are read from top to bottom and left to right but the text as a whole is written in horizontal lines, left to right. There are many Chinese spoken languages but they all use the same script, which is intelligible to all of them, even though the spoken languages may be very different. Mandarin is the language used as the official language of China. It is fairly easy for a Westerner to distinguish spoken Chinese from Japanese and Korean because it is a 'tonal' language where the meaning of any particular word may depend on the pitch and the change of pitch used in speaking the word. To a Western ear, this sounds 'sing-song' and is easily distinguished from the other two. Neither Japanese nor Korean have this feature (though, of course, they have tonal variations over a whole sentence, as English and, in fact, all languages do - a question has a different tonal pattern from a statement or a command) and, because I am not very familiar with the sound of Korean, I think I would not be able to identify the language on hearing them spoken.

The scripts don't show, but I can definitely tell Hangul apart from Japanese and Chinese. I probably couldn't tell you Japanese writing from Chinese. I can tell you if someone is speaking Chinese, Korean or Japanese a lot easier.