血药浓度

A. Half of the world needs to take the water issue seriously.
B. Water safety is something the world must take action on.
C. Water is linked to creating jobs and conditions of work.
D. Protecting the environment is important to access to water.

A. The wealth gap.
B. Poor health care.
C. Slow economic development.
D. Unequal water resources.

A study of Asia's water problems and their causes.
B. MIT's new solutions to increasing water supply.
C. Scientists' prediction of climate change in Asia.
D. The future of the world's industrial development.

A. Economic and political factors.
B. Social and cultural factors.
C. Geographical and climate factors.
D. Human and natural factors.