2011年1月18日，杭州下了今年的第一场雪，出现了严重的冰冻。为使道路积雪消融，环卫工人使用了氯化钠、氯化钙等“化冰盐

解题思路：融雪剂融雪和防止路面结冰的原理：融雪剂溶于水后，使含盐雪水的凝固点降至0℃以下，使路面积雪难以结冰，氯化钠、氯化钙、氯化镁溶于雪水形成的溶液属于电解质溶液．

A．用“化冰盐”融雪属于物理变化，故A错误；
B．MgCl₂也可用作“化冰盐”形成电解质溶液，故B正确；
C．使用“化冰盐”不会使水分子结构发生变化，故C错误；
D．大量使用“化冰盐”会造成水资源的污染，故D错误．
故选B．

点评：
本题考点： 物理变化与化学变化的区别与联系．

考点点评： 本题考查物理变化化学变化的区别，“化冰盐”融雪的原理，难度不大．

D

Today our class went outing to a forest near our school .We start on 10am, It costed we one hour by bus . When we arrived the forest , we were so excited , we never came to visit a forest . There were so many kinds of animals and trees , We were told that some animals and trees were even dangerous to people , so we should be careful in the forest .Trees were taller than these we saw in the city ,and the flower were everywhere and colorful , butterfly were flying over it. Birds were singing in the sky , resting no the tree .
We left the forest on 4pm .After this travel , I learned many things ,I could speak some animals and trees' name , I though the forest were man's big wealth that we should protect it . I love the forest .

2009年5月6号到2010年5月5日共365天.
2010年5月6日 2011年1月5日=31*5+28+30*2=243天
2011年1月6日到2011年1月18日=13天
共365+243+13=621天