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“北京，下土了”．2006年4月，北京遭遇多年来最严重的沙尘暴袭击．专家指出，沙尘暴在带来严重危害的同时，也能够在一定程度上中和掉酸雨的影响，减少酸雨的形成．

（1）沙尘暴袭击时，使得这一地区空气中______含量增加．

A．O2   B．N2    C．SO2   D．可吸入颗粒物

（2）据以上信息推测，沙尘暴可能呈______性（填“酸”“碱”或“中”性）．

（3）完成下列实验，证明你的推测．

    实  验  步  骤    实验现象
①取样：取约2g沙尘于试管中，加少量水，振荡后过滤

②取少量滤液于试管中，滴1～2滴酚酞试液

酚酞试液变______．
（4）若用pH试纸来检验，则滤液的pH______ 7（填“＜”“＞”或“=”）．

答案

（1）空气的主要污染物有颗粒物质、一氧化碳、二氧化硫、氮的氧化物、碳氢化合物等，沙尘暴袭击使使空气中的颗粒物增加，故（1）答案：D

（2）专家指出，沙尘暴在带来严重危害的同时，也能够在一定程度上中和掉酸雨的影响，减少酸雨的形成；碱能和酸发生中和反应，故（2）答案：碱  

（3）酚酞能使碱变红色，故（3）答案：红  

（4）碱性物质的溶液的pH大于7故（4）答案：＞

听力题

根据短文内容和首字母提示，在下文空格处填入适当的词使短文完整。在答题卡标有题号的横线上，写出空缺处各单词的正确形式。（每空一词）

Once there was a baby eagle（鹰） living in a nest （巢）on a cliff（山崖）. The baby eagle loved his nest. It was warm, soft, and comfortable. And even b 小题1:, he had all the food and love. When the baby eagle was h__小题2:___, his mother would always come just in time with the delicious food.

He was growing h____小题3:____ day after day. But suddenly his world changed one day. His mother stopped coming to the nest. He was full of s___小题4:___ and fear. He thought he would die soon. He cried, but nobody heard him.

Two days later, his mother a___小题5:___with some nice food. The baby eagle was wild with joy. But his mother put the food at the top of the m____小题6:_____ and then looked down at her baby. The baby eagle cried out. “Mum, why did you do this to m__小题7:___? I’m hungry. I will die if I have nothing to eat.”

“Here is the l___小题8:____ meal that I give you. Come and get it by yourself,” his mother said. Then she flew down and pushed the baby eagle out of the nest.

The baby eagle f___小题9:____ down, faster and faster. He looked down at the earth. The ground was much closer. Then something strange happened. The air caught behind his arms and he began to fly! He wasn’t moving to the ground any more. Instead, his eyes were pointed up at the sun.

“You are f___小题10:____! You can make it!” his mother smiled.
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多项选择题

下列关于直接经验和间接经验，错误的说法有( )

A．直接经验是认识的“流”

B．间接经验是认识的“源”

C．直接经验往往是感性认识

D．间接经验往往是理性认识
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