21.   Farmers elsewhere are able to learn about crop diseases and resistant strains from the Web.

22.   Giving new drugs to people who do not truly need them, he said, will only speed the emergence of resistant strains of parasites.

23.   If they have active TB, they pass the resistant strain on to the general population when they leave.

24.   If this happens often enough, the resistant strains could create a significant public-health problem.

25.   In other parts of the globe, from China to Siberia to Puerto Rico, strains resistant to at least four of the five common drugs have emerged.

26.   Interruption of the therapy can promote the emergence of a resistant strain of HIV.

27.   It is imperative that this disease be brought under control before the resistant strains proliferate and put much of the globe at risk.

28.   Or make a plant insect-proof, and you are damned for encouraging a more resistant strain of insect.

29.   Patients who do not continue with therapy will find themselves infected with only the resistant strains of virus, making the disease more difficult to treat.

30.   Otherwise, the resistant strains of HIV could enter the developed world.