yes ,and this is my aunt's son,my ( ),David.This girl is my cousin ,too.( )is David'Ssister ,Rose

yes ,and this is my aunt's son,my ( ),David.This girl is my cousin ,too.( )is David'Ssister ,Rose
yes ,and this is my aunt's son,my ( ),David.This girl is my cousin ,too.( )is David'S
sister ,Rose

yes ,and this is my aunt's son,my ( ),David.This girl is my cousin ,too.( )is David'Ssister ,Rose
cousin she

cousin
She
因为，cousin 这个词可以指堂表兄弟姐妹。要根据具体语境选择男或是女的搭配。

cousin，she