Earth Day（世界地球日）

    Earth Day was first observed in Spring of 1970. An estimated 20 million people nationwide attended festivities out of which came the largest grassroots environmental movement in U.S. history, and the impetus¹ for national legislation like the Clean Air and Clean Water Acts. By the twentieth anniversary of that event, April 22, 1990, more than 200 million people in 141 countries participated in Earth Day celebrations.
    Former U.S. Senator Gaylord Nelson, Earth Day's co-founder, modeled Earth Day on anti-Vietnam War demonstrations³, called "teach-ins," that were common on college campuses. "At a conference in Seattle in September 1969, I announced that in the spring of 1970 there would be a nationwide grassroots demonstration² on behalf of the environment," says Nelson. "The response was electric. Telegrams, letters, and telephone inquiries⁴ poured in from all across the country." As many as 20 million Americans participated in environmental rallies, demonstrations and other activities in the 1970 Earth Day.
    Since the first Earth Day, however, the environmental movement has increasingly transformed itself from a largely grassroots, citizen crusade to a professionally-organized, established special interest.

1 impetus   

n.推动，促进，刺激；推动力

参考例句：

• This is the primary impetus behind the economic recovery.这是促使经济复苏的主要动力。
• Her speech gave an impetus to my ideas.她的讲话激发了我的思绪。

2 demonstration   

n.表明，示范，论证，示威

参考例句：

• His new book is a demonstration of his patriotism.他写的新书是他的爱国精神的证明。
• He gave a demonstration of the new technique then and there.他当场表演了这种新的操作方法。

3 demonstrations   

证明( demonstration的名词复数 )； 表明； 表达； 游行示威

参考例句：

• Lectures will be interspersed with practical demonstrations. 讲课中将不时插入实际示范。
• The new military government has banned strikes and demonstrations. 新的军人政府禁止罢工和示威活动。

4 inquiries   

n.调查( inquiry的名词复数 )；疑问；探究；打听

参考例句：

• He was released on bail pending further inquiries. 他获得保释，等候进一步调查。
• I have failed to reach them by postal inquiries. 我未能通过邮政查询与他们取得联系。 来自《现代汉英综合大词典》