问题 解答题

用计算器产生四位数的随机数,记录你所得到的前100个数,如果没有计算器你将怎样进行这项实验?观察你的实验数据,能有哪些发现?汇总全班同学的数据能有什么新发现?

答案

4位数中的每一个数都可能出现,可让班内50个同学任意写2个四位数,组成100个数,记录结果;

观察你的实验数据,可得一个4位数出现的频率与计算得到的概率不一定相同;

汇总全班同学的数据,可得一个4位数出现的频率与计算得到的概率接近,那么实验次数越多,所求的频率接近于理论上的概率.

单项选择题
阅读理解

阅读理解。

     Downing the last drop of an expensive famous brand H2O as weIl as remembering to

throw the empty bottle in the recycling bin.makes you feel pretty good about yourself, right?

It shouldn't. Even when the bottles are recycled, there are all kinds of otherconsequences of

swallowing bottled water, says Melissa Peffers, the air-quality program manager for

Environmental Defense.

    The containers are often filled in foraway lands, then shipped from abroad,and stored in

refrigerators at your local store. Compare that with the influence on environment of turning

on your tap ,filling a glass,and drinking up!

    Anyone who is choosing bottled water for health reasons ismisguided,says Peffers,"Most

bottled water is just tap water." And what comes out of your tap is carefully monitored to

follow the strictrules. Consider another fact that bottled water is surprisingly expensive.

especially when compared with the altemative,which is almost free ,andit is astonishing that

America's desire for bottled water seems impassibleto satisfy,reaching nearly 30 billion

bottles a year.

    "My parents' generation never  had  bottled water, "saysIsabelle Silverman,an

Environinental Defense legal adviser. She hasmade a commitment to going bottle free."You

don't need to fetch ithome from the store,and it's cheaper, " she adds

Bottled water's role as a status symbol needs to change,Pefferspoints out. So when a waiter

at an expensive restaurant offers"Andwhat's your drink?"that's no reason to forget your

conviction(信念). "Don't be afraid to say,'I'll have tap.' Say it loud enoughthat the other

tables nearby can hear you,"Peffers says,"And thenspend that money on a dessert. "

1. In the first paragraph,the underlined sentence"It shouldn't."suggest that people________.

A. shouldn't feel pleased with finishing the water in the bottle

B. shouldn't feel good about drinkinl an expensive brand H2O

C. shouldn't be content with just recycling empty bottles

D. shouldn't be satisfied with drinking only bottled water

2. According to the author, tap water is_________. 

A. as safe as bottled water

B. more likely to be polluted

C. healthier than bottled water

D. less convenient than bottled water

3. The underlined part"going bottle free"(in Paragraph 4)means"______". 

A. making bottled water free

B. abandoning bottled water

C. recycling used water bottles

D. providing free water containers

4. Why does Peffers ask people to say"I'll have tap."loudly?

A. To encourage them to set an example for others to follow.

B. To advise them to save the money for one more dessert.

C. To remind them to be aware of their social status.

D. To persuade them to speak confidently in public.