since about six years 是错误的.
since 用于现在完成时中,后面跟过去的时间或者跟一般过去时的动作.
例如：
She has lived here since about six years ago.
=She has lived here since 2007.
since的用法：since后面可以接什么
since about six years 是错误的.
since 用于现在完成时中,后面跟过去的时间或者跟一般过去时的动作.
例如：
She has lived here since about six years ago.
=She has lived here since 2007.