Statistics resulting from careful investigations show that there

Statistics resulting from careful investigations show that there have been over ______ languages in the world, about two thirds of which have not had written form.
A、5,000
B、4,000
C、4,500
D、3,000
【正确答案】：A
【题目解析】：Statistics resulting from careful investigations show that there have been over 5,000 languages in the world, about two thirds of which have not had written form.