since about six years 是錯誤的.
since 用于現(xiàn)在完成時中,后面跟過去的時間或者跟一般過去時的動作.
例如：
She has lived here since about six years ago.
=She has lived here since 2007.since for about six years正確嗎？since for about six years是錯誤的。正確的說法是：since about six years ago或者是 for about six years