An elephant and a monkey lived in the same forest. One day they went to ask an old bird, “Can you tell us which is ____ important, being strong or being quick?"The old bird didn't give them the answer at once. Instead, he ____ them to get some bananas the other side of the river and bring them to him.

    So the elephant and the monkey went to the river, but the____ ran so fast that monkey was afraid. "Get on my back, Monkey,” said the elephant, “I shall take you there. I'm big and strong, I can swim____ the river."

    Soon they got to the other side. The elephant____hard to reach the bananas, they were too high."Wait a ____, please. I can climb,” said the monkey. He quickly ran up to the ____ and passed the bananas to the elephant.

    Then they came ____ happily to the old bird and showed him the bananas. Now, you see, the elephant is strong,” said the old bird____ a smile, but he couldn't get the bananas. The monkey is quick, but he couldn't cross the river. Only you two could do the work well when you helped ____other.”

 为了除去粗盐中的Ca²⁺、Mg²⁺、SO₄^2﹣等离子，可将粗盐溶于水后进行如下操作：①加入适量盐酸，②加过量NaOH溶液，③加过量Na₂CO₃溶液，④加过量BaCl₂溶液，⑤过滤．下列操作顺序合理的是（　　）

“食客”准备着

下列选项中，属于相对性状的是（　　）

有一个阴湿性山洼草丛中，有一堆长满苔藓的腐木，其中聚集着蚂蚁、蚯蚓和蜘蛛、老鼠等动物，这些生物它们共同构成了一个