题干

下面甲图示洋葱根尖分生区连续分裂的细胞在各个时期细胞核内DNA含量的测定结果,乙图是一组目镜标有5×和16×字样、物镜标有10×和40×字样的镜头,丙图是某同学在乙图中选用的一组能放大160倍的镜头组合所观察到的图像。欲将丙图视野中处于甲图e时期的细胞移至视野中央进行640倍的高倍镜观察,正确的镜头组合及移动装片方向应是

A:(1)×(4);左上方

B:(1)×(3);右下方

C:(2)×(3);右下方

D:(2)×(3);左上方

上一题 下一题 0.0难度 选择题 更新时间:2013-09-06 07:59:08

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D

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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.