1. It is not necessary for you to work on Saturdays -> You don't....................... 2. Mark is an American, but he plays Vietnamese folk games well. -> Although.........

1. It is not necessary for you to work on Saturdays
-> You don't........................................................
2. Mark is an American, but he plays Vietnamese folk games well.
-> Although..................................................................
3. It is wrong of you to throw rubbish on the street.
-> You mustn't....................................................................