单项选择题

At the Kyoto conference on global warming in December 1997, it became abundantly clear how complex it has become to work out international agreements relating to the environment because of economic concerns unique to each country. It is no longer (21) to try to forbid certain activities or to reduce (22) of certain substances. The global challenges of the inter-link between the environment and development increasingly (23) us to the core of the economic life of states. During the late 1980s we were able, through international agreements, to make deep (24) in emissions (25) the ozone layer. These reductions were made possible (26) the harmful substances could be replaced (27) negative effects on employment and the economies of states.
Although the threat of global warming has been known to world for decades, we know that the effects of measures, (28) harsh measures taken in some countries, would be nullified if (29) countries do not control their emissions. Important and populous low- or medium-income countries are not (30) willing to undertake legal commitments about their energy uses. We must, (31) find a solution to the threat of global warming early in the 21^st century. Such a (32) would require a degree of shared vision and common responsibilities new to humanity. Success lies in the force of imaginations, in imagining what (33) if we failed to act. Although many living in cold regions would welcome the global-warming effect of a warmer summer, (34) would cheer arrival of the (35) tropical diseases, especially where there has been none.