The next few decades will see the world experience many most pressing challenges, one of which is how to ease the __（1）__ stress that human activities are placing on the environment. The consequences are just too great to __（2）__. Wildlife habitats are being degraded or disappearing altogether as new developments __（3）__ more land. Plant and animal species are becoming __（4）__ at a greater rate now than at any time in Earth’s history. As many as 30 percent of the world’s fish stocks are over-exploited. And the __（5）__ goes on.

       __（6）__, there is reason to have hope for the future. Advances in computing power and molecular biology are among the tremendous increases in __（7）__ capability that are helping researchers __（8）__ a better understanding of these problems. Recent development in science and technology could provide the __（9）__ for some major and timely actions that would __（10）__ our understanding of how human activities affect the environment.

      Improving hydrological forecasting is one priority for research. It has been __（11）__ that the world’s water use would triple in the next two decades. Already, widespread water __（12）__ have occurred in parts of China, India, and North Africa. The need for water also is taking its toll on fresh water ecosystems in the United States. Only 2 percent of the nations’ __（13）__ are considered in good condition , and __（14）__ to 40 percent of native fish species are rare to extinct.

      To prevent __（15）__ ofinfectiousdiseases in plants, animals and human, more study is needed on how parasites and disease-carrying species—as __（16）__ as humans and other species they __（17）__ ---are affected by changes in the environment. The overuse of antibiotics both in humans and in farm animals has __（18）__ to the growth of antibiotic-resistant micro organism. Researchers can take __（19）__ of new technologies in genetics and computing to better monitor and __（20）__ the effects that environment changes might have on diseases outbreaks.