题目

Since the first Earth Day in 1970,Americans have gotten a lot “greener” toward the environment(环境).“We didn’t know at that time that there even was an environment,let alone that there was a problem with it,”says Bruce Anderson,president of Earth Day the USA. But what began as nothing important in public affairs has grown into a social movement.Business people,political leaders,university professors,and especially millions of grass-roots Americans are taking part in the movement.“The understanding has increased many,many times,”says Gaylord Nelson,the former governor fr用双线桥法标出下列氧化还原反应电子转移的方向和数目，并指出氧化剂、还原剂。（1）MnO2+4HCl(浓)MnCl2+Cl2↑+2H2O（2）2H2S+SO23S↓+2H2O