某生物兴趣小组研究在生产果汁的过程中果胶酶的最适用量．合理设置果胶酶用量的梯度后，可通过苹果泥出汁的多少来判断酶的用量是否合适．请根据所给的材料和用具完成以下探究实验．

（1）材料用具：

  制备好的苹果泥、恒温水浴装置、试管、漏斗、滤纸、量管、试管夹、质量分数为2%的果胶溶液、质量分数为0.1%的NaOH溶液和盐酸．

（2）实验步骤：

  ①取6支试管，编号1～6，分别加入____ ，调节pH至4.8．

  ②向1～6号试管中分别加入____ ，然后放入45℃恒温水浴装置中____ ．

  ③过滤苹果泥并记录____ ．

（3）实验分析：

  ①该实验的自变量是____ ，因变量是____ ．

  ②酶的活力通常用____ 来表示，即酶促反应过程中单位时间内底物的减少量或产物的生成量来表示．

    Once, a rich man was near death. He was very upset because he had worked so hard for his money ____ he hoped he could take it with him to heaven. So he prayed to God he might be able to take some money with him.

    ____ angel heard his pray and appeared. “Sorry, ____  you can't take your wealth with you.” The man begged the angel to speak to God to see ____ he might break the rules. The angel reappeared and said that God could allow him to take one suitcase. Excitedly, the man gathered his suitcase and filled it ____ pure gold bars.

    Afterward, he died and showed up in heaven to greet St. Peter. ____  (see) the suitcase, St. Peter said, “Hold on, you can't bring that here!” The man explained that he had God's ____ (permit). St. Peter checked it out, came back and said, “You are right. You are allowed one carry-on bag, but I'm supposed to check its contents ____ letting it through.”

    St. Peter opened the suitcase to inspect（检查）the things ____ the man found too precious to leave behind and exclaimed (感叹), “You brought paving(铺路的) stones? As you can see, the great street of the city of heaven ____ (make) of pure gold!”

新疆维吾尔自治区今后的经济发展方向是（　　）