There are four people in one place in a revolving restaurant, and language problems occur in convers

At the banquet table of the International Hotel, four friends, A, B, C, and D, had an interesting conversation, and they spoke in four languages: Chinese, English, French, and Japanese.

At the banquet table in the International Hotel, four friends, A, B, C, and D, had an interesting conversation, and they spoke in four languages: Chinese, English, French, and Japanese, and also knew that A, B, and C each knew two languages, and D only knew one language; There is a language that 3 out of 4 people can speak; A can speak Japanese, D does not know Japanese, B does not know English;