EACH of the United States' three major news networks has its own flagship news program: ABC's World News with Charles Gibson; the CBS Evening News; and NBC Nightly News. These programs, unlike that at CCTV, the Xinwen Lianbo, air at 6:30 pm and are presented by a major anchor person on weekdays. On weekends, they are presented by correspondents, at a different time. They battle each other over higher ratings and try to establish their own unique style (something that's not easy).