读“地震波速度与地球内部构造图”，回答下列问题：

利用图甲装置探究“MnO₂的用量对H₂O₂分解反应的影响”，实验中H₂O₂的溶质质量分数为3%，装置中产生氧气的量可以用压强传感器测出（在等温条件下，产生氧气体积与装置内压强成正比．反应放热忽略不计。）

语法填空

阅读下面短文，按照句子结构的语法性和上下文连贯的要求，在空格处填入一个适当的词或者使用括号中词语的正确形式填空。

In the tenth grade, I worked at an animal hospital in my spare time. I wanted to get experience for my future job. However, I  ____(get) something more important.

  The hospital ____(lie) in a poor place of the city. One Saturday, a man and his little son walked in and opened a box  ____(careful). There was a cat in the box, and something was wrong ____ the cat’s left eye. But the man didn’t have enough money to pay for the medicine. He kept quiet for a while, and then he asked where ____(near) animal shelter was. Hearing this, his son____(cry). At that time, an old woman walked up to them and told the man that she would pay for the medicine. The man thanked her and the son got to keep a ____(health) cat.

  I always thought it was the right thing to help a person  ____ was in trouble, but I only saw that ____ TV or in movies before. What the woman did made me believe that these things did happen in real life. Now, when I can’t decide whether to help someone in need 30. ____ not, I think of this woman, and then I have the courage to do it.