logic questions

Give a critical evaluation of each of the following passages
5. "The First Amendment forbids the government from prohibiting the free exercise of religion. Therefore, the government cannot prohibit religions from engaging in human sacrifice." (Daniel E. Flage, Logic, 1995)
  
6. If cigarette smokers are warned of the hazards of smoking and they continue to smoke, then they cannot sue tobacco companies for any resulting lung cancer or emphysema. Cigarette smokers are warned of the hazards of smoking. Therefore, if cigarette smokers continue to smoke, they cannot sue tobacco companies for any resulting lung cancer or emphysema. (Hurley, A Concise Introduction to Logic, 1997)
  
7. Some pornographic publications are protected under the "free speech" provisions of the First Amendment. For this reason, it is false to say that no pornography is protected by the First Amendment.
  
8. "Wherever the national diet is rich in wheat bran, the incidence of colon cancer is low. The national diet in Canada is not rich in wheat bran. Thus, in Canada, the incidence of colon cancer is not low." (Hurley, A Concise Introduction to Logic, 1997)