胶体区别于其他分散系的本质特征是（ ）

A．能产生丁达尔效应

B．胶体颗粒做布朗运动

C．胶体微粒带电荷

D．分散质直径在1nm~100nm之间

—_____ are the Olympic Games held, do you know?

—Every four years. [ ]

A. How soon

B. How far

C. How long

D. How often