如果发现水中S042-降低，则有可能是有（）等沉积。A、Fe203 B、H2S C、

按要求改写句子。

1. When he was eight, he began to learn the accordion. （改为同义句）

    ______________ eight, he began to learn the accordion.

2. The girl looks after the baby well. （改为同义句）

    The girl ______________ the baby.

3. It takes about 15 minutes to walk home.（对画线部分提问）

    ______________ it to walk home?

4. I went home after I finished my homework.（改为同义句）

   I _____________ home until Ifinished my homework.

5. I think Liu Ying is not as tall as her sister.（同上）

    I think her sister is _____________ Liu Ying.

B

It is natural that children are curious about the world around them. For example, they want to know how their hearts beat. They want to know why the ocean water tastes salty.

　　As children grow up, they become curious about different kinds of things. When they are babies, they are interested in the parts of their bodies and in the smiles of their mothers. They become interested in the physical world around them: the plants, the animals, the sky. Later, they become interested in the things that people have made: wheels, bicycles, cars. And when they are adults, their curiosity continues. Sometimes this curiosity leads to a career (生涯、职业) in science.

　　Scientists spend their lives trying to find out about the world．Those who work with the earth sciences study the earth, the oceans, and the skies. Other scientists who study living things work with the biological sciences. A third group of scientists study the physical sciences, e. g. physics, chemistry .

　　These scientists have already discovered a lot about our world．For example, they tell us why your heart beats fast when you run. They say that when you are quiet, your heart normally beats sixty-five or seventy-five times a minute. Your heart is a pump (泵) that pumps blood to all parts of the body. The blood carries oxygen and nutrition. When you run, your muscles work very hard and use the nutrition that the blood carries to them. The muscles need oxygen, too . So your brain sends a signal to the heart. The signal means that the muscles need more nutrition and oxygen. Then the heart beats fast and sends blood quickly to the muscles. It may beat 90 to 140 times a minute.

　　Of course, scientists cannot answer all of our questions. If we ask, “Why does the ocean water taste salty” scientists will say that the salt comes from rocks. When a rock gets very hot or very cold, it cracks. Rain falls into cracks. The rain then carries the salt into the earth and into the rivers. The rivers carry the salt into the ocean. But then we ask , “What happens to the salt in the ocean? The ocean does not get saltier every year.” Scientists are not sure about the answer to this question.

　　We know a lot about our world, but there are still many answers that we do not have, and we are curious.

45．According to the passage, which of the following statements is true?

　  A．People are curious in the same way.

　  B．People in different countries are interested in different things.

　  C．Men and women are curious about different things.

　  D．People of different ages are interested in different things

46．Scientists who work with the biological sciences study____.

A．the earth , the oceans and the sky          B．man-made things

C．plants and animals                               D．ocean water

47．When you run, your muscles need ____.

A．more nutrition and oxygen    B．more signals    C．more salt   D．water

48．A rock cracks _____.

A．in wet regions                                     B．in dry regions

C．at very high or very low temperatures               D．when salty water falls in

（9分）已知T℃、p kPa时，往容积可变的密闭容器中充入2 mol X和1 mol Y，此时容积为VL。保持恒温恒压，发生反应：2X（气）+Y（气）2Z（气），达到平衡时，平衡气中Z的体积分数为0.4。试回答下列有关问题：

（1）使温度和压强在上述条件下恒定不变，再往上述密闭容器内充入4molZ，则反应达到平衡时，容器的容积为             ，平衡气中Z的体积分数为               。

（2）若另选一个容积固定不变的密闭容器，仍控制温度为T℃，使3molX和1.5molY反应，达到平衡状态时，平衡气中Z的体积分数仍为0.4，则该密闭容器的容积为           。

关于丙型肝炎病毒和丁型肝炎病毒的描述中，不正确的是（）。

A.均为RNA型病毒

B.均需要依赖乙型肝炎病毒（HBV）完成其病毒复制

C.均主要为经输血注射途径传播

D.均可有慢性携带者

E.均可导致慢性肝炎、肝硬化

在客户信用评级中，由个人因素、资金用途因素、还款来源因素、保障因素和企业前景因素等构成，针对企业信用分析的专家系统是( )。

A．5Cs系统

B．5Ps系统

C．CAMELs分析系统

D．51ts系统