地球上的水在不停地循环着：阳光晒暖了海洋，水变成水蒸气升到空中，形成暖湿气流；暖湿气流遇到冷空气后，水蒸气变成了小水滴，形成雨降落到地面．以下说法中正确的是（　　）

      It was the first day of biology class. The teacher wanted to give a good1  to his class. He wanted to  2  his students’ eyes to the world of biology.
      He knew that 3  young students was not easy, so he worked 4  and tried to find a good way to teach this class.5  thinking for a long time, he made a 6  at last. He decided to show the kids something7 and teach them a lesson at the same time.
      He asked his students to 8  carefully. Then he began. He put a worm(虫子) into a glass of water. The worm 9 around in the water. Then he put a second worm into a glass full of alcohol(酒精). It died at once. He asked the students if anyone knew about 10 they learned from it. A boy said, “You showed us that if we drink alcohol we won't have worms.”

朝秦暮楚这一个成语出自于春秋战国时期的（   ）

抗生素是我国老百姓最熟悉、也是最容易被“滥用”的药物。复旦大学对江苏、浙江、上海1000多名在校儿童尿液进行检查，结果显示，近6成儿童检出尿液中含有抗生素。食品药品应是主要途径之一，预防性使用抗生素是典型的“滥用”抗生素，“滥用”抗生素会对人体产生毒副作用；特异体质的人还会产生过敏反应而导致休克；另外大量使用抗生素无疑是对致病菌抗药能力的“锻炼”，使其抗药性增强。“超级细菌”很大程度上就是抗菌药物“滥用” 催生出来的。如果这种情况继续恶化下去，很可能使人类面临感染时无药可用的境地。(本大题共10分)

在粗盐提纯的实验中，蒸发时正确的操作是（　　）