决定焊件是否需要预热以及预热温度的因素有（）。A．钢材的化学成分 B．焊件尺寸大小

2012年3月15日是第30个国际消费者权益日，中国的主题确定为“消费与安全”。为此，该校打算举办一次以“食品消费与安全”为主题的实践活动。请你参与到活动中，完成下列要求：

（1）请提供一种方法，调查本校学生在食品消费方面存在的问题。

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（2）为了营造活动氛围，请你围绕主题设计一条宣传标语。

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（3）当你购买食品时，应该注意哪些事项？

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（4）如果你的合法权益受到侵犯，正确的态度是什么？

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（5）下面是学生小王当天在微博上的留言，请帮他完成留言。

     People have often wondered about Margaret Thatcher's famous claim that she only needed four

hours of sleep a night. People were amazed that former British Prime Minister had managed to run the

country on so little sleep. Most people need at least seven or eight hours rest every night.

     But now scientists have discovered a gene(基因)that affects the amount of sleep we need and which

allows some people to survive on fewer hours. They found a mother and a daughter who have a rare

gene that allows them to sleep less than the rest of their family -but still feel alert during the day. The pair

managed to stay alert on about six hours sleep a night, two hours less than the rest of their family needs.

     The finding, published in Science magazine, offers a new direction for studies on how sleep affects

health. Experts say adults need seven to nine hours of sleep for good health, while teenagers and kids

need more. People who don’t get enough sleep are more likely to get sick and suffer from memory loss.

     In 2001,scientists at the University of California discovered a mutation(突变)in a gene that causes

people with that gene to have very unusual sleeping patterns. These people go to bed around 7:30 pm

and wake around 3:30 am.

     Now the team has found a gene that affects how long a person can stay asleep. In the family they

studied, the 69-year-old mother and her 44-year-old daughter usually went to bed around 10 pm. The

mother woke up around 4 am, and her daughter woke up around 4:30 am. Both of them felt fully rested.

     Blood tests showed the women have a mutation in a gene named DEC2, which regulates the body's

clock.

     Researcher Ying-Hui Fu bred(培育) mice and fruit flies to carry the mutation. The flies and mice with

the mutation slept less than ordinary flies and mice, and needed less time to recover from little sleep.

1. What is the main idea of the passage?

A. Less sleep does not affect people's health.

B. Different people have different sleeping patterns.

C. New measures can reduce the effect of less sleep on health.

D. The hours we need to sleep may be affected by some gene in our body.

2. The underlined word "alert" in Paragraph 4 is similar in meaning to        .

A. comfortable

B. wide awake

C. quite alive

D. sleepy

3. In the study, the mother and the daughter       .

A. were found to have a mutation in the gene DEC2

B. were asked to sleep less than other family members

C. had the same sleeping pattern as other family members

D. suffered from memory loss for sleeping only six hours a night

4. According to the passage, the new finding can help       .

A. recover memory loss

B. cure sleeping problems

C. get rid of mice and fruit flies more easily

D. explain why some people need less sleep to feel fully rested

与两项浸提技术相比较，两重浸提技术既可以在高真空下，也可以在低真空条件下使用潜水泵或者空气泵工作。

妊娠恶阻肝热型的表现

A．呕吐胃内容物

B．呕吐酸苦水

C．呕吐痰涎

D．呕吐物带血丝

E．食入即吐

用于消化道造影检查的对比剂为（）；用于子宫输卵管造影检查的对比剂为（）。