题干

按如图所示装置进行实验(图中铁架台等仪器均已略去).先在试管Ⅱ中加入试剂乙,然后在试管Ⅰ中加入试剂甲,立即塞紧橡皮塞,一段时间后,观察到试管Ⅱ中有白色沉淀生成.符合以上实验现象的一组试剂是(   )

A:甲:NaHCO3、稀HCl    乙:NaOH

B:甲:Al、稀H2SO4       乙:Ba(NO32溶液

C:甲:MgO、稀盐酸       乙:AgNO3

D:甲:Cu、稀H2SO4       乙:BaCl2溶液

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B

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    Rick Garcia is going to play outside with his friends. He is taking out his reliever inhaler (缓解物吸入器) and taking two puffs (吸). Five minutes later, he's on the field with his friends, running after a soccer ball. Rick has asthma (哮喘), but he knows how to control it.

    Asthma is a lung disease. A person with asthma may cough or suffer from shortness of breath. Asthma can begin at any age. Childhood asthma, often beginning when a child is younger than 10 years old, is one of the most common childhood diseases. Doctors report that the number of young people with asthma is increasing. It is the number one cause of absence from school. If parents have asthma, their children are more likely to develop the disease. Children in homes where an adult smokes are more at risk.

    It is important to find out the triggers for asthma. As we know, dust, pollen, or animals often make people suffer from asthma. Once a child learns the triggers, he can help prevent future attacks. About half of all children outgrow asthma and then asthma attacks stop when they are teenagers. However, many people live with the disease into adulthood.

    Children often take control drugs once or twice a day to help prevent asthma attacks, if a child begins to have an asthma attack, a quick-relief drug is also necessary. This is often an inhaler. School-aged children usually carry their inhalers with them. This medication works quickly and children begin to breathe more easily in a few minutes. If a child has a serious asthma attack, he may need full-time care at a hospital or a doctor's office.