成人英语三级考试

【单选题】The main reason for the population growth isn't so much a rise in birth rates ______ a fall in death rates as a result of improvements in medical care.


A．and
B．but
C．or
D．as

网考网参考答案：B
网考网解析：
not so/as…as…意为“不如……”，not…but…意为“不是……而是……”。 查看试题解析出处>>