如何区别usually和ofen?

usually—in the way that is usual; most often(80%),副词,“通常地；惯常地”。例如：What do you usually do on Sundays?你星期天通常做什么?He’s usually early。他通常到得早。The canteen is more than usually busy today。今天食堂比往常忙得多。often—many times; at short intervals; frequently(30—50%),副词,“常常；经常；时常”。例如：We often go there。我们常去那儿。We have often been there。我们经常在那里。He writes to me often。他经常给我写信。