1973年，根据周恩来指示，国家计委提出：在今后三五年内，从国外进口一批技术先进的成套设备与单机，价值43亿美元。在当时被称为“四三方案”。这一方案（    ）

Smoking too much will       your health greatly.

    Andy is 12 years old. He is one of my best f____. He is a top student in Class 6. But he doesn't have a good diet.

    Every morning, he doesn't eat breakfast. It isn't right. I think breakfast is very i____ for him. It helps him start the day w____. He has lots of snacks like chocolates, sweets every day. They make him fat. It's bad for his health. Andy shouldn't eat too many snacks any more. In vegetables and fruits there are many vitamins. But he h____ eating them. These days he doesn't feel good.

    I think he needs to c____ his diet. And he needs to exercise more. I'm sure he'll be better.

实验室利用过氧化氢、氯酸钾、高锰酸钾等物质制取氧气，其原因是（   ）