单项选择题
A．are done in a week B．aren't very clear C．are done in 24 hours D．take a long time
A．255 were originals B．45 were originals C．85% were fakes D．155 were originals
A．they ask other teachers to read their students' papers B．they ask their students to list their sources of information C．they can sign up for the Internet service D．they search the Internet and compare papers