12.    On Friday evening, sometimes I go to the cinema, sometimes I stay at home and watch TV. (EITHER)

⇒ On Friday evening, sometimes I either go to the cinema or stay at home and watch TV

13.    I like neither watching TV nor reading a novel before going to bed. (EITHER)  

⇒ I don't like either watching TV or reading a novel before going to bed

14.    They can't begin working on Monday. They can't begin working on Wednesday. (EITHER) 

⇒  They can begin working neither on Monday nor on Wednesday

15.    My sister didn't watch TV last night. She didn't listen to music last night. (EITHER)   

⇒ My sister didn't either watch TV or listen to music last night