BSpending two or three hours playing outdoors each day can reduce a child’s chance of becoming short-sighted, a research shows. It challenges (挑战) the belief that short- sightedness is caused by computer use, watching TV or reading in weak light.The Austr

题目

B

Spending two or three hours playing outdoors each day can reduce a child’s chance of becoming short-sighted, a research shows. It challenges (挑战) the belief that short- sightedness is caused by computer use, watching TV or reading in weak light.

The Australian government researchers believe that sunlight is good for people’s eyes. They compared the vision(视力) and habits of 100 seven-year-old children in Singapore and Australia. In all, 30% of the Singaporean children were short-sighted--this rate(比率) was ten times higher than Australian children.

Both groups spent a similar amount of time reading, watching television and playing computer games. However, the Australian children spent an average(平均) of two hours a day outdoors—90 minutes more than the Singaporean children.

Professor(教授) Ian Morgan, from the Australian Research Council’s Vision Centre, said, “Humans are naturally long-sighted, but when people begin to go to school and spend little or no time outdoors, the number of short-sighted people gets larger. We’re also seeing more and more short-sighted children in cities all around the world—and the main reason may be that city children spend less time outdoors. “

Daylight can be hundreds of times brighter than indoor light. But why does playing outside prevent us from becoming short-sighted? Scientists believe that natural light has a special chemical(化学物质) which stops the eyeball from growing out of shape and prevents people becoming short-sighted.

So be outdoors. It doesn’t matter if that time is spent having a picnic or playing sports.

24. How much time did the Singaporean children spend outdoors on average every day in the research?

A. 2 hours. B. 90 minutes. C. 1 hour. D. 30 minutes.

相似考题

1.以下对枚举类型名的定义中正确的是______。A．enum a={one,two,three};B．enum a{on=9,two=-1,three};C．enum a={"one","two","three"};D．enum a{"one","two","three"};

2.以下对枚举类型名的定义中正确的是______。A．enum a={one, two,three}；B．enum a{one=9,two=1，three}；C．enum a={"one"，"two","three"}；D．enum a{"one", "two"，"three"}；

3.以下对枚举类型名的定义中正确的是 ( )A．enuma＝{one，two，three}；B．enuma{one＝9，two＝-1，three}；C．enum a＝｛"one" "two"，"three"}；D．enum a{"one"，"two"，"three"}；

4.以下对枚举类型名的定义中正确的是______。A．enum a={one,two,three}；B．enum a{one=9，two=-1,three}；C．enum a={"one"，"two"，"three"};D．enum a{"one"，"two"，"three"}；

更多“B Spending two or three hours playing outdoors each day can reduce a child’s chance of be ”相关问题

  • 第1题：

    Despite the wonderful acting and well-developed plot the _________ movie could not hold our attention.

    A) three-hours B) three-hour

    C) three-hours’ D) three-hour’s

     

     


    选B

     用破折号连接的作形容词不用复数.

  • 第2题：

    以下对枚举类型名的定义中正确的是

    A．enum a {one=9,two=-1,three};

    B．enum a={“one”, “two”, “three”};

    C．enum a {“one”, “two”, “three”};

    D．enum a={one, two, three};


    enum a｛a1,a2,a3｝;

  • 第3题：

    5、以下对枚举类型名的定义中正确的是（）。

    A．enum a={one,two,three};

    B．enum a{one=9,two,three};

    C．enum a={"one","two","three"};

    D．enum a{"one","two","three"};


    enum a {one=9,two=-1,three};

  • 第4题：

    以下对枚举类型名的定义中正确的是______。

    A．enum a={one,two,three};

    B．enum a {one=9,two=1,three};

    C．enum a={"one","two","three"};

    D．enum a{"one","two","three"};


    正确答案：B
    解析：声明枚举类型用enum开头。例如：enumweekday(sun,mon,tue,wed,thu,fri,sat)；说明：1、在C编译中，对枚举元素按常量处理，同时可以改变他们的值。2、枚举值可以用来做判断比较。3、一个整数不能直接赋给一个枚举变量。

  • 第5题：

    8、以下对枚举类型名的定义中正确的是

    A．enum a {one=9,two=-1,three};

    B．enum a={“one”, “two”, “three”};

    C．enum a {“one”, “two”, “three”};

    D．enum a={one, two, three};


    enum a｛a1,a2,a3｝;

  • 第6题：

    以下对枚举类型名的定义中正确的是（）。

    A．enum a={one,two,three};

    B．enum a {one=9,two=-1,three};

    C．enum a={"one","two","three"};

    D．enum a {"one","two","three"};


    A

相关内容