《圣经》里把两河流域描绘成“人类幸福的伊甸园”，这里曾孕育的文明国度是（    ）

Do you have any foreign friends? Do you know their characteristics(特征)?
The Germans are very quiet and they always keep calm. They don't like to speak more words. They look very serious. They like different kinds of amusements. The Germans are very hard—working. They like tidiness, especially the women, who always keep their home clean.
In some ways, the Englishmen look the same as the Germans. They are very quiet and never talk too much with the strangers. They are really polite, so we often hear they say "Thank you."Or "Sorry."The gentlemen are also the Englishmen.
The French's holidays are very long. They like traveling and usually spend their long time staying in other countries. The Frenchmen are more outgoing than the Germans. It is very easy to make friends with them.
Compared to the Frenchmen, the Americans are more outgoing. And they are even opener than all of the Europeans. They don't like to depend on others. So it is very common that the students do part-time jobs in their free time. And in Americans' eyes, success is an important part in their life.

三种物质间只通过一步反应就能实现如箭头所指方向的转化，下列符合要求的组合是（　　）