频度副词的特点:频度副词表示动作发生的次数,常见有的:ever, never, rarely, seldom, once, often, occasionally, constantly, frequently, usually, continually, always 等。频度副词在否定句中的位置:在否定句中,有的频度副词可位于否定词not之后或之前(如usually, often),有的频度副词则必须位于否定词之后(如always, constantly, continually, continuously,均含有“连续不断”之意),而有的频度副词却必须要位于否定词not之前(如sometimes, frequently)。