题干

下列物质属于混合物的是____  ,属于金属单质的是____ ,属于氧化物的是____ ,存在氧分子的是 ____ .(填序号)

①不锈钢;②氧气;③冰水混合物;④净化后的空气;⑤高锰酸钾;⑥二氧化碳;⑦澄清的石灰水;⑧锌.

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答案(点此获取答案解析)

①④⑦,⑧,③⑥,②④

同类题2

研究人员用同种小鼠进行了某中药制剂、四环素(一种抗生素)对肝脏脂肪含量影响的实验.实验设计和结果如下表所示(中药制剂和四环素都用生理盐水溶解),请据表分析回答:

组别

除每天喂养相同的饲料外,进行如下处理

在第11天测量并计算每组小鼠肝脏脂肪的平均含量(mmol•L﹣1)

连续11天每天喂下列试剂

同时第8天至第11天每天腹腔注射下列物质

甲组

等体积生理盐水

等体积生理盐水

0.49

乙组

等体积生理盐水

0.025mmol四环素

6.51

丙组

中药制剂(0.05g)

0.025mmol四环素

4.74

丁组

中药制剂(0.10g)

0.025mmol四环素

4.52

戊组

中药制剂(0.15g)

0.025mmol四环素

4.10

(1)若要观察小鼠皮下脂肪细胞中的脂肪颗粒,可用____ 染色.

(2)现有健康的体重相近、发育状况相同的雌雄小鼠各100只,按上表的实验设计应将这些小鼠进行分为五组,每组的情况为____ ,表中所示的实验自变量有____ .

(3)甲组和乙组对照可说明腹腔注射四环素导致____ .上表实验结果可初步说明该中药制剂能____ (填“降低”或“升高”)肝脏脂肪的累积量(增加量).

(4)研究人员认为,要证明某中药制剂对肝脏脂肪含量的影响,还需要观察中药制剂对没有注射四环素的小鼠肝脏脂肪含量的影响.请完善实验设计并回答问题:

Ⅰ.实验步骤:

①步骤一:按上表所示的实验设计的要求增加3组小鼠,并编号.

②步骤二:这3组小鼠除每天喂养相同的饲料外,每天还需分别喂0.05g、0.10g、0.15g的中药制剂,共11天.同时在第8至11天注射____ ,保持其它条件相同且适宜.

③步骤三:测量并统计实验结果.

Ⅱ.讨论:

①将得到的实验结果与上表的____ 组的结果进行对照,然后得出结论.

②步骤二中需要“保持其它条件相同且适宜”,其原因是除需保持单一变量使各组之间有对照外,还需____ .

同类题3

完形填空

    Last winter vacation, my brother got a set of bedroom furniture for his thirteenth birthday. When it arrived, I helped my parents moved the 1 furniture to the garage(车库). It was still in good condition. I thought it might be a chance for us to 2 someone in our community. I started to search neighbors, anyone who 3 a bedroom set. Finally, my mom helped me call the local primary school. They told me about Jaila, the daughter of a poor single mother. I was given a telephone number and 4, and I soon found myself at Jaila's.

    The moment I went into Jaila's room, I knew I had taken on too big a task. When I pushed the old door open, it made a long high noise. But the door was nothing compared with the rest of the room. Some old paint was 5 the wall. One of the windows was 6 The bed was just a mattress(床垫)on the old carpet. It seemed that the room needed7furniture — it cried — for a complete makeover(翻新).

    That day I spent at least an hour looking around and 8how I could possibly fixed the room. I had never painted a wall, let alone fixed a floor. The second day, I returned with a large group of helpers — my close friends. We went to collect everything needed door to door in our community. We replaced and repainted Jaila's room. We sweated in Jaila's house for more than ten hours every day that week.

    The moment we finished, we called Jaila into the room. She jumped, laughed and hugged each of us. I turned to Jaila's mother, and saw she had tears running down her face.

    “Anna,” Jaila called my name9.

    “Yes?”

    “Welcome to my new room!”

    When we saw how happy Jaila and her mother were, our tiredness disappeared into thin air. We are really 10 to make a special experience of changing someone's life.