问题
选择题
A salty diet may increase the risk of stomach cancer ________ 10 percent, South Korean researchers found in a study of more than 2 million people．
A．at
B．to
C．by
D．for
答案
答案：C
这题考查介词的用法：increase by“增加了”，句意是：盐份多的食物会增加胃癌的几率10%。选C。