当飞机降落时，乘务员要求旅客咀嚼食物，其目的是使耳中的____ 张开，使鼓膜内外的____ 保持平衡，从而防止对耳的损伤．

请从下列常见仪器图示中，选择恰当的字母序号填空．

①可以直接在酒精灯火焰上加热的玻璃仪器是____、名称是____

②镁条燃烧时，用来夹持镁条的仪器是____；名称是____

③用酒精灯加热时需要垫上石棉网的仪器是____；

④取用粉末状固体药品用到的仪器是____；名称是____．

根据短文理解, 从A、B、C、D四个选项中选择最佳答案填空。

    One cold morning, an old woman had to 1 her doctor. When he came, she 2 him that her right leg hurt, and that sometimes she could  3 walk. She asked him what was  4  , as she had  5got such feeling.

    The doctor looked her over carefully, and then he said, "You are in a good 6  for a woman of your age. I think the trouble in your right leg is just a matter of old age catching up with you. We get all kinds of illness  7  we get older. The trouble will almost certainly 8  in spring." "I don't think so, doctor," she said. "My left leg is  9 , and it is 10  age as my right leg."