某交流电电源电压的瞬时值表达式为u=6sinl00πt（V），则下列说法中正确的

下列做法合理的是(　　)。

A．电视机着火用水扑灭

B．随意丢弃废旧电池

C．草木灰与铵态氮肥混合施用

D．用活性炭除去冰箱内的异味

高炉软融带的形状是高温区分布与（）的综合表现。

烧伤创面处理的目的是（）

A．减少或避免瘢痕形成

B．防止感染

C．尽可能在短时间内封闭创面

D．最大限度恢复功能

E．减轻损害及疼痛

阅读理解。

     A new study has found no evidence that sunscreen, commonly used to reduce the risk of skin cancer,

actually increases the risk.

     Researchers from the University of lows based their findings on a review of 18 earlier studies that looked

at the association between sunscreen use and melanoma (黑素瘤). They said that they found flaws in studies

that had reported associations between sunscreen use and higher risk of melanoma.

     Most health experts believe that by protecting the skin from the harmful effects of the sun, sunscreen

helps prevent skin cancer, which is increasing in incidence (发生率) faster than any other cancer in the

United States.

     But questions have been raised about sunscreen and whether it may have the opposite effect, perhaps

by allowing people to remain exposed to the sun longer without burning.

     The researchers said that among the problems with some earlier studies is that they often failed to take

into account that those people most at risk for skin cancer-people with fair skin and freckles (雀斑), for

example-are more likely to use sunscreen. As a result, it may appear that sunscreen users get cancer more

often.

     The studies, which generally relied on volunteers to recall their sunscreen use, were also unable to prove

how well the products had been applied, said the new study.

1. The underlined word "flaws" in the 2^nd paragraph most probably means _____.

A. evidences

B. facts

C. faults

D. failures

2. People with fair skin and freckles _____.

A. seldom use sunscreen

B. are more in danger of skin cancer

C. can be free from the harm of the sun

D. often expose themselves to the sun

3. We can learn from the passage that _____.

A. sunscreen users get skin cancer more often

B. the volunteers have proved the effect of sunscreen

C. the new study was based on the experiences of volunteers

D. the number of skin cancer patients is increasing in America

4. Which of the following can be the beat title for this passage?

A. Sunscreen to Prevent Skin Cancer

B. Sunscreen to Increase Skin Cancer

C. Skin Cancer Caused by Sunscreen

D. Skin Cancer Caused by Freckles

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