One day, a little schoolboy went home with a pain in his stomach.

    "Well, sit down and 1 a cake," said his mother."Your stomach 2hurting because it's empty.It'll be all right when you've got something in it."

    Five minutes later, Dad came home 3 the office.And he said he had a headache.

    "That's because your head is 4," said his clever son."You'll be all right if you have got 5 in it." His dad and mum laughed.

夏日里想随时喝到凉爽的饮料，可以自制化学“冰箱”，即把一种化学试剂放入一定量的水中，就可以形成低温的小环境，这种试剂可以是下列物质中的（ ）

全面贯彻落实科学发展观，必须大力提高自主创新能力，把科技进步和创新作为经济创新型国家和人力资源强国。我国大力推进科技创行是因为（　　）

①科学技术是第一生产力，科技创新是一个国家的生命和灵魂

②科学技术是综合国力的重要基础，科技创新能增强国家实力

③实施创新驱动发展，把科技创新摆在国家发展全局的核心位置

④国际关系是变化发展的，科技竞争是国际关系的重要内容之一。