题目

请根据下列研究氧气、空气和二氧化碳性质等的实验装置图，回答有关问题。 （1） 从物质分类的角度看，空气属于(填“混合物”或“纯净物”) （2） 从构成物质的微粒看，铁丝在氧气中燃烧是铁原子与氧分子发生化学反应，请用化学符号表示：3个铁原子：，2个氧分子：。 （3） 从宏观现象的角度看，实验C的现象为，由可知二氧化碳的性质有，，。 （4） 从变化过程的角度看，某同学对B装置改进后如图D所示，实验时，从完形填空。通读下面的短文, 掌握其大意, 然后从各题所给的A、B、C三个选项中选出一个最佳答案。George lived with his sick mother in a poor village.One bright sunny _____ in July， he went early to the forest two miles away. He was asked to _____ some wood from under the trees. After working hard for half a day， he looked around for a ______ place to rest and eat his lunch. Suddenly some fine red wild _____ caught his eyes.“How good these will be with my bread and butter!” thought George. He at once began to _____ all the strawberries he could find and sat down by the river， ready to enjoy them.Just then as he was lifting the _____ strawberry to his mouth， he thought of his mother. “shall I _____ them for her?” said he， thinking how much they would make _____ happy， yet still looking at them with longing (渴望的) eyes.“ I will eat half， and take the other half to her，” said he. Then he divided the strawberries into two. _____ he found each half looked so small that he put them together again.“I will only taste one.” Then seeing that he taken the biggest， he put it back. Finally he _____ them carefully with some leaves， deciding to keep all _____ his mother.When the sun was beginning to go down， George went home. _____ happy he felt that he had all his strawberries for his sick mother. The _____ he came to his home， the less he wished to taste them. As soon as he arrived， he ran to his _____ and happily offered his wild strawberries. Tears in eyes， she put her hand on his head and said _____ ， “And you kept them for your sick mother， did you? God will bless you for all this， my child.”Could the eating of the strawberries have given George half the happiness he felt at the moment.1.A. morning B. noon C. afternoon D. night2.A. set up B. pick up C. put up D. give up3.A. hot B. dark C. cool D. noisy4.A. apples B. strawberries C. pears D. peaches5.A. buy B. grow C. make D. collect6.A. first B. last C. other D. next7.A. cut B. peel C. sell D. keep8.A. him B. them C. her D. it9.A. But B. So C. If D. Or10.A. showed B. locked C. covered D. washed11.A. to B. from C. for D. on12.A. What B. How C. Why D. Whether13.A. nearer B. farther C. longer D. later14.A. father B. sister C. friend D. mother15.A. angrily B. lovingly C. worriedly D. politely