vissim系统时间:usually often 那个更频繁一点？

usually often 那个更频繁一点？ often 的usually区别 区别 sometimes always often usually !!!???? always，often， usually 如何区别？ usually often sometimes 的用法 often 和 usually有什么区别？那个表示频率更高一些？ 谢谢 often 和 usually有什么区别？那个表示频率更高一些？ 谢谢 always, often, usually 该如何区分? usually often sometimes 的用法是什么 ___does he usually go with?He often ___with his father.