1.作頻度副詞用法：放在be動詞和助動詞后面；行為動詞前.
特殊用法：
1 sometimes可以放在句首、句中和句末
2 often 也可以放在句末
如：
Tom never went to see his wife.．(在行為動詞之前)
Tom has never been to China.．（在第一個助動詞后）
Tom is never late for school.（在系動詞后）
屬于這一類的副詞還有often,sometimes,always,usually,already,nearly,almost等.
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2.作頻度狀語,一般都用于完成時.
1）i've never seen such a beautiful place.
2）this is the most beautiful place i've ever seen.