单选题 The main reason for the fast growth of population is not ______ a rise in birth rates as a fall in death rates as a result of improvements in public health service and medical care.
A. such B. the same
C. so much D. as much

【正确答案】 C
【答案解析】此句用的是not...so much...as“与其说……不如说……”结构。句意是：“人口快速增长的主要原因与其说是出生率提高，不如说是由于医疗保健工作的改进使死亡率下降。”