Have you ever planted a few trees on Tree Planting Day? Each year, millions of people, both 1 , plant a lot of trees. But this may not be the best way to make your home a 2 place.

    Last week we visited a park in Hebei. We were 3 to find most of the trees had been burned. The workers told us that the trees 4 soon after they were planted because they weren't watered well enough. 5 workers burned them and cleaned the place for 6 trees to be planted this year. 7 a card found in one of the dead trees, a student wrote,“ I hope this tree will grow up with me to 8 the backbone (栋梁) of our country.” The workers said that the survival(存活) of the trees was really more important than 9 trees were planted.

    Some people in Beijing now have a new idea that they can donate (捐赠) some money and let professionals (专业人士) plant and 10 the trees.

统一是人心所向，大势所趋。维护统一，巩固统一，始终是历史发展的主题。那些有利于国家统一的人或事在历史的长河中依然被后人传诵与铭记。阅读下列材料：

……

江山如此多娇，

引无数英雄竞折腰。

惜秦皇汉武，略输文采；唐宗宋祖，稍逊风骚。

一代天骄，成吉思汗，只识弯弓射大雕。

俱往矣，数风流人物，还看今朝。

──毛主席诗词《沁园春•雪》

请回答：

已知f(x)dx＝56，则(　　)