U.S. No Longer Tallest Country in the World
America used to be the tallest country in the world. From the days of the founding fathers right on through the industrial revolution and two world wars, Americans literally towered over other nations. In a land of boundless open spaces and limitless natural abundance, the young nation transformed its increasing wealth into human growth. However, just as it has in so many other arenas, America's predominance in height has faded. Americans reached a height plateau after World War II, gradually falling behind the rest of the world as it continued growing taller.
By the time the baby boomers reached adulthood in the 1960s, most northern and western European countries had caught up with and surpassed the United States. Young adults in Japan and other prosperous Asian countries now stand nearly as tall as Americans do. Even residents of the formerly communist East Germany are taller than Americans today. In Holland, the tallest country in the world, the typical man now measures 6 feet, a good two inches more than his average American counterpart. Compare that to 1850, when the situation was reversed. Not just the Dutch, but all the nations of western Europe, stood 2 1//2 inches (6.25 em) shorter than their American brethren.
Does it really matter? Does being taller give the Dutch any advantage over say, the Chinese (men 5 feet, 4.9 inches; women 5 feet, 0.8 inches) or the Brazilians (men 5 feet, 6.5 inches; women 5 feet, 3 inches)? Many economists would argue that it does matter, because height is correlated with numerous measures of a population's well being. Tall people are healthier, wealthier and live longer than short people. Some researchers have even suggested that tall people are more intelligent. It's not that being tall actually makes you smarter, richer or healthier. It's that the same things that make you tall—a nutritious diet, good prenatal care and a healthy childhood—also benefit you in those other ways.
That makes height a good indicator for economists who are interested in measuring how well a nation provides for its citizens during their prime growing years. With one simple, easily collected statistic, economists can essentially measure how well a society prepares its children for life. This is the part of the society that usually eludes economists, because economists are usually thinking about income. This is the part of the society that doesn't earn an income. Height tells you about a segment of the population that is invisible to traditional economic statistics. Children don't have jobs or own houses. They don't buy durable goods, or invest in the stock market. Obviously, investments in their well being are critical to a nation's economic future.
For several years now, researchers have been trying to figure out exactly why the United States fell behind. How could the wealthiest country in the world, during the most robust economic expansion in its history, simply stop growing? Maybe we've reached the point where we're going to go backwards in height. Like many human waits, an individual's height is determined by a mix of genes and environment. Some experts put the contribution of genes at 40%, some at 70%, some even higher. However, they all agree that aside from African pygmies and a few similar exceptions, most populations have about the same genetic potential for height. That leaves environment to determine the differences in height between populations around the world, specifically the environment children experience from the moment of conception through adolescence. Any deficiency along the way, from poor prenatal care to early childhood disease or malnutrition, can prevent a person from reaching his or her full genetic height potential. We know environment can affect heights by three to five inches (7.5 to 12.5 cm). The earliest stages of life are the most important to the human growth machine; at age 2 there is
A.shorter than
B.about the same height as
C.taller than
第1题
A.在成员函数声明的前面加上virtual修饰,就可把该函数声明为虚函数
B.基类中说明了虚函数后,派生类中对应的函数也必须说明为虚函数
C.虚函数可以是另一个类的友元函数,但不能是静态成员函数
D.基类中说明的纯虚函数在其任何派生类中都必须实现
第2题
A.在成员函数声明的前面加上virtual修饰,就可把该函数声明为虚函数
B.基类中说明了虚函数后,派生类中对应的函数也必须说明为虚函数
C.虚函数可以是另一个类的友元函数,但不能是静态成员函数
D.基类中说明的纯虚函数在其任何派生类中都必须实现
第3题
下面关于虚函数的描述,错误的是()。
A.在成员函数声明的前面加上virtual修饰,就可把该函数声明为虚函数
B.基类中说明了虚函数后,派生类中对应的函数也必须说明为虚数
C.虚函数可以是另一个类的友元函数,但不能是静态成员函数
D.基类中说明的纯虚函数在其任何派生类中都必须实现
第4题
下面关于虚函数的描述,错误的是
A.在成员函数声明的前面加上virtual修饰,就可把该函数声明为虚函数
B.基类中说明了虚函数后,派生类中对应的函数也必须说明为虚函数
C.虚函数可以是另一个类的友元函数,但不能是静态成员函数
D.基类中说明的纯虚函数在其任何派生类中都必须实现
第5题
下面关于虚函数的描述,错误的是
A.在成员函数声明的前面加上virtual修饰,就可把该函数声明为虚函数
B.基类中说明了虚函数后,派生类中对应的函数也必须说明为虚函数
C.虚函数可以是另一个类的友元函数,但不能是静态成员函数
D.基类中说明的纯虚函数在其任何派生类中都必须实现
第6题
下面关于虚函数的描述,错误的是
A.在成员函数声明的前面加上virtual修饰,就可把该函数声明为虚函数
B.基类中说明了虚函数后,派生类中对应的函数也必须说明为虚函数
C.虚函数可以是另一个类的友元函数,但不能是静态成员函数
D.基类中说明的纯虚函数在其任何派生类中都必须实现
第7题
下面关于虚函数的描述,错误的是()。
A.在成员函数声明的前面加上virtual修饰,就可把该函数声明为虚函数
B.基类中说明了虚函数后,派生类中对应的函数也必须说明为虚函数
C.虚函数可以是另一个类的友元函数,但不能是静态成员函数
D.基类中说明的纯虚函数在其任何派生类中都必须实现
第8题
下面关于虚函数的表述中正确的是()。
A.虚函数不能声明为另一个类的友元函数
B.派生类必须重新定义基类的虚函数
C.如果在重定义虚函数时使用了保留字virtual,那么该重定义函数仍是虚函数
D.虚函数不能够声明为静态函数
第9题
下面关于虚函数的表述中正确的是()。
A.虚函数不能声明为另一个类的友元函数
B.派生类必须重新定义基类的虚函数
C.如果在重定义虚函数时使用了保留字virtual,那么该重定义函数仍是虚函数
D.虚函数不能够声明为静态函数
第10题
下面关于虚函数的表述中正确的是()。
A.虚函数不能声明为另一个类的友元函数
B.派生类必须重新定义基类的虚函数
C.如果在重定义虚函数时使用了保留字virtual,那么该重定义函数仍是虚函数
D.虚函数不能够声明为静态函数
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