一个空瓶质量是200 g，如果装满水总质量是700 g，今先向瓶内装一些金属颗粒，使瓶和金属颗粒总质量为1 kg，然后再向瓶内装满水，则三者质量为1410 g，问：瓶内装的是什么金属？

23. 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