好发于儿童青少年的卵巢肿瘤是（）。 A.性索间质肿瘤 B.生殖细胞肿瘤 C.转移性癌

离子间能大量共存，当溶液中c（H⁺）=10^-1mol•L^-1时有气体产生，而当溶液中c（H⁺）=10^-13mol•L^-1时又能产生沉淀．下列各组离子中符合上述要求的一组是（　　）

A．Ba²⁺K⁺CO₃^2-Cl^-

B．Na⁺K⁺NO₃^-CO₃^2-

C．Mg²⁺NH₄⁺SO₃^2-Cl^-

D．Fe²⁺Na⁺SO₃^2-NO₃^-

阅读理解。

     Rising levels of carbon dioxide in the atmosphere are a major cause of climate change, and now a new

study has confirmed that atmospheric CO₂ is also affecting the ocean chemistry and potentially harming

sea life.

     Montana State University scientist Robert Dore has been researching the water in the Pacific Ocean for

almost two decades.

     "We've been going to the same spot in the Pacific Ocean, and we try and characterize long-term change

in the open ocean environment. And one of the key things that we measure is CO₂ levels. And we've been

able to record this increasing quantity of atmospheric CO₂ into the ocean."

     Scientists expected that as atmospheric CO₂ increased, more and more of the carbon dioxide would be

absorbed into the ocean, affecting the chemical balance of the sea water, with a potentially harmful impact

on shellfish and coral in particular.

     "As carbon dioxide dissolves (溶解) in the water or seawater in this case, it forms a weak acid, carbonic

acid," Dore explains. "And therefore, as the concentration of CO₂ in the atmosphere goes up and that

exchanges with the surface seawater, it drives the pH down, and makes it more acidic."

     The seawater Dore and his colleagues have analyzed confirms what the theory predicts.

     The effect was particularly striking at about 250 meters down, and again at 500 meters. Dore and his

colleagues came up with two possible explanations. It could be that surface water picked up CO₂ and then

moved to those depths. Or there could be a biological explanation.

     "It's important to realize that the oceans are really becoming acidic. And it could have negative impacts

on a whole variety of sea life from fish to coral. It's potentially catastrophic."

1. What can be the best title of the passage?[ ]

A. Sea Life Facing Danger

B. Scientist Researching Seawater

C. Oceans Becoming More Acidic

D. Climate Change Affecting Seawater

2. With the increase of atmospheric CO₂, _____. [ ]

A. more corals will appear in the sea

B. the surface water is becoming warmer

C. the chemical balance of the seawater is affected

D. the pH of the ocean out here has been increasing

3. Which of the following shows the process of the impact of atmospheric CO₂ on sea life?

    a. Sea life is endangered.

    b. CO₂ goes into the surface water.

    c. The ocean chemistry is affected.

    d. CO₂ decreases the pH and makes the seawater more acidic.

    e. CO₂ levels in the atmosphere go up. [ ]

A. a→b→c→d→e

B. e→b→c→d→a

C. a→e→b→c→d

D. e→d→c→b→a

4. Scientist Robert Dore came to the conclusion based on _____. [ ]

A. his research and analysis

B. the expectation of other scientists

C. some former theory

D. a major cause of climate change

5. What does the passage want to tell us most? [ ]

A. It takes time to make a scientific study.

B. Atmospheric CO₂ is doing harm to sea life.

C. Robert Dore is a committed and serious scientist.

D. Measures should be taken to prevent the potential catastrophe.

下列肾脏疾病中，常见不到钙化斑的是

A．肾结石

B．肾癌

C．肾囊肿

D．肾结核

E．肾错构瘤

SF6气体在电弧作用下会产生何种物质？有无危害？检修人员应注意什么？