问题 选择题

将下列试剂分别滴入氢氧化钠溶液、饱和石灰水和稀硫酸中,能产生三种不同现象的是(  )

A.硫酸钠溶液

B.氯化钠溶液

C.紫色石蕊试剂

D.碳酸钠溶液

答案

A、硫酸钠和三种物质都不会反应,不能鉴别,故A错误;

B、氯化钠和三种物质都不会反应,不能鉴别,故B错误;

C、紫色石蕊试剂在氢氧化钠和氢氧化钙中显蓝色,现象相同,不能鉴别,故C错误;

D、碳酸钠不会与氢氧化钠反应,和氢氧化钙会生成碳酸钙沉淀,会与硫酸反应生成二氧化碳气体,现象不同,可以鉴别,故D正确;

故选D.

改错题

短文改错。

     假如英语课上老师要求同桌之间交换修改作文,请你修改你同桌的以下作文。文中共

有10处语言错误,每句中最多有两处。每处错误仅涉及一个单词的增加,删除或修改。

     增加:在缺少单词处加一个漏字符合(^),并在其下面写出该加的词。

     删除:把多余的词用斜线(\)划掉。

     修改:在错的词下划  横线,并在该下面写出修改后的词。

     注意:1.每处错误及其修改均仅限一词;

                  2.只允许修改10处,多者(从第11处起)不计分。

Dear Susan,

     I am very glad to hear you are come to visitme the next Friday. Unfortunately, I won't be able to meet

you at the airport although I have classes in the afternoon. You won't find difficult to get to the city center. The airport bus leaves every 30 minute and will take you rightly to the Friendship Hotel. My class will be

over by then or I will pick you up there. I will take you together to a hot-pot restaurant for dinner and

we'll talk with our plan for the weekend overdinner. Having a pleasant trip and see you this Friday.

                                                                                                                       Yours,

                                                                                                                     Zhang Ming

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