[填空题]enormous

[填空题]
The enormous differences in Chinese dialects have been a continuing problem ever since China became an empire in 221 B. C. , and it is one big reason why the country has remained impoverished (贫穷). Of the 600 million people who call themselves Chinese, all but a very small number speak Chinese. But the dialects vary so widely that the speech of Peking, for example, is as different from the speech of Canton as English is from German.
There is to be sure, only one written language for all China, but it bears no phonetic(语音的)relationship to any of the spoken dialects. Moreover, it has so many symbols that only a tiny portion of the population has ever mastered it.
As a result, most Chinese have been isolated for centuries from a free flow of ideas and from the economic progress that such a flow produces. Many dynasties tried with little success to break down the wall. After recognizing the importance of

[填空题] The enormous growth of American economy has been 【B1】 to many factors. The size of the United States and its 【B2】 resources have been often cited as important reasons for the rapid 【B3】 of American economy. They are true to a great extent. But, then, there are other countries in the world that are 【B4】 with similar natural conditions and yet have 【B5】 developed to the same degree of economic power as the United States has. So, there must be reasons 【B6】 the size the country and the natural resources it possesses. According to the 【B7】 . argument, the remarkable achievements of the U. S. economy are primarily 【B8】 the system 【B9】 which it has been operating since the founding of the nation- American capitalism. It is true that American capitalism should be 【B10】 with the achievements of its economy, the question 【B11】 immediately comes to our mind is what are the essential 【B12】 and construct their significance in the 【B13】 of A
A. A．other than
B．rather than
C．in addition
D．why