桑杏汤的功用是：
A．养阴清肺
B．清燥润肺
C．轻宣温燥
D．养阴润肺
E．润肺化痰
参考答案：C
The chief 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．as
C．but
D．or
