你可以把often放在句首,這樣就容易理解了.這里的often修飾這個句子,做狀語.
------- （Very）often,it is the case that / when - - - - - .你的說法靠譜，但是比如都是頻度副詞的twice a year、once a week與often the case差不多，那么：Twice，he go shopping a week這種句子貌似沒見過-_-|呵呵， twice a week是個短語，不能分割，不過你可以把這個短語放在句子開頭，照樣達(dá)到同樣的效果。那么就是說類似often這樣的副詞都可以在主系表這種結(jié)構(gòu)的句子中做單獨的狀語嗎？能幫我再舉個例子嗎，最好是放在句子里的，不要句首的^_^1 She's always too busy working to look after her family members.
== Always is she too - - -- -.
2 They are never pleased with her work.
== Never are they pleased -- - -
3 He's sometimes seen to play football in the street.
== Sometimes he's seen - - - -