If you don't know the person's gender, you can call（ ）.

单项选择题13. What can we infer about the university system of the USA? A、A. Most of the people can receive higher education. B、B. Only the outstanding people can go to university. C、C. A small amount of college graduates are outstanding. D、D. The majority of college graduates are outstanding.

单项选择题双绞线只能传输数字信号，不能传输模拟信号。（ ） A、正确 B、错误