鸟的飞行器官是（　　）

 

某研究小组用下图所示装置，探究能否用镁条代替红磷测定空气中氧气含量。

实验前，小组成员提出了不同的猜想。

【猜想与假设】

猜想1：可以代替，因为镁条与氧气反应后不会产生气体

猜想2：不能代替，查阅资料知金属镁很活泼，可能会与空气中的氮气反应

【进行实验】

步骤	实验操作	实验现象
Ⅰ	组装好装置后，打开止水夹，手捂集气瓶，一段时间后，松开手	烧杯中导管口有气泡冒出，松手后，烧杯中导管末端有一段液柱
Ⅱ	关闭止水夹，点燃镁条，迅速伸入集气瓶中，塞好塞子	镁条燃烧，放出大量热，发出耀眼白光，生成大量白烟，剩余固体为白色带状物
Ⅲ	冷却至室温，打开止水夹	烧杯中水从导管进入集气瓶中，体积约为集气瓶体积的2/5

【解释与结论】

若近地面的气温低于0℃，从天空降落的雨滴，与地物接触后即刻冻结的天气现象称为冻雨。下图示意我国南方某地1月24日至30日垂直方向的气温变化，读图完成下列各题。

如图为细胞结构示意图，请据图回答：

短文改错。
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    One day when I was still a primary school pupil, I got back home after school and find Daddy sitting in a chair reading. “Daddy, there is going to have a parents' meeting this evening, you're requiring to attend it,” I said to him with a low voice. Hearing this, Daddy started to comb his hair. When anything was almost ready, I begged him to take me with him. So he did it. When we got to the school gate, Daddy was surprised to find that was strangely quiet in the school. Look at his puzzled face, I told him that it was just a small meeting and that we two were only people invited. Daddy seemed to understand everything and he had to go ahead.