Certain species of whales are in danger of extinction. Some court procedures are so complicated as to be very inefficient. No Russian authors are insensitive to nature. The ozone layer around the earth could be damaged by frequent use of aerosol spray cans. Use conversion, obversion, and contraposition to determine whether the following arguments are valid.
All commodity traders are gamblers who risk sudden disaster.
Therefore, all gamblers who risk sudden disaster are commodity traders. No child abusers are persons who belong in day-care centers. Therefore, all child abusers are persons who do not belong in day-care centers. Some insane are people are illogical people. Therefore, some logical people are sane people.