86. Form the microbiologists, we learn that contaminated drinking water ____.

1. is not limited to poor and developing nations
2. is neglected in poor and developing countries
3. is associated only with poor and developing nation
4. has become more serious in rich nations than in poor countries

87. Where there is a spread of waterborne disease, ____.

1. there is a distribution of water laden with pathogens
2. there is an increasing demand for water
3. there is a week supply of water
4. All of above.

88. What makes things worse according to the microbiologists?

1. Chemicals are used to treat and disinfect water.
2. Pathogens can be transmitted in contaminated water.
3. Some waterborne pathogens are hard to find in contaminated water.
4. Some waterborne pathogens are becoming resistant to the chemical used.

89. People in industrialized countries are easier to catch disease because ____.

1. most of them are aged
2. they are in poor health
3. they are not strong immune to waterborne pathogens
4. they have never been challenged by any infection before

90. As the author implies, water treatment plants ____.

1. rely on unreliable "indicator" organisms
2. cannot ensure a supply of safety water
3. Are badly needed to treat and disinfect water
4. are using new method to detect pathogenic bacteria, viruses and protozoa

(Reference keys.)