题目

根据所给的汉语写出单词，使句子意思完整正确。 51. Our classroom isn’t as clean as     ▲     (平常) after exams. 52. It’s such a    ▲   (令人愉快的) trip that I will remember it for ever. 53. The final-term exam is coming soon. The students are busy    ▲   (准备)for it. 54. Amy is such a clever girl that she learned to cook by     ▲     (她自己) at 8. 55. In my school, students not only work hard, but also take part in all kinds of    ▲   (活动), such as dancing, drawing, reading and so on. 56. The old woman 以油脂为原料可以制取高级脂肪酸和甘油，也可以用来制取肥皂。工业上制高级脂肪酸和甘油时选择______________(填“酸性”“碱性”或“中性”)条件，其反应类型为__________，化学方程式为______________；若制取肥皂和甘油，则选择______________条件，其反应类型为______________，化学方程式为___________________________________________。