Omnivores usually are not vegetarians. Some omnivores are not vegetarians. No professors are poor lecturers. All poor lecturers are nonprofessors. Some professors are not poor lecturers.
Some poor lecturers are professors.
Some poor lecturers are nonprofessors. Exercise 10-5 1. Some scientists are impractical. Type I. 9. All professors who forget useless trivia are failures on TV quiz shows.