Mrs. Green is________ mother. They are________.
A:Lucy and Lily's; twins
B:Lucy's and Lily's; twins'
C:Lucy and Lily's; twin
新疆的西瓜很甜,这一现象主要是由下列哪种因素决定( )
①七七事变 ②九一八事变 ③西安事变 ④中共七大