she is behaving in the same way ()her sister used to

she is behaving in the same way ()her sister used to D
Bin which
Clike
Das
我觉得in which 就是in the way 没什么错啊

behave行为
used to 过去常常
分句的意思是，她妹妹过去常常（做的那样）
主句是，她以同样的方式处世。什么样的方式呢，正如她妹妹过去常常处世的方式。所以这句话的意思是，她处世的方式正如她妹妹一样。
she is behaving in the same way as her sister used to.
she is behaving in the same way in which her sister used to do.
区分一下吧

is 后面加not来 否定。 同样are 后面加 not  ；can 后面加 not； must 后面加 not；do 后面加 not等等。 一般在系动词（im, is ,are）、情态动词(can，must，need...)、助动词(do，does)后面加not来表示否定。

as有正如,好像得意思 "her sister used to do"才用in which /that