TOEFL Reading: ETS-TOEFL阅读机经 - 26D8XC7OP0UI4D68L$

Which of the following is NOT identified in paragraph 3 as a factor contributing to the greater stability and success of the Eastern empire A. A shorter border subject to invasion by Germanic tribes B. Greater cultural unity among the inhabitants C. More resources available for achieving political goals D. Lower population densities outside of urban areas