问题
单项选择题
Since Jonas Salk came up with his polio vaccine, infantile paralysis has virtually disappeared from the United States.
A．surfaced with
B．raised the price of
C．discovered
D．elevated
答案
参考答案：C
解析：[分析] 习语辨析。 come up with想出，提出，提供；raise the price of抬高……的价格：discover (首次)发现，发觉，找到；因此C为答案。