____ it would be silly to argue any longer. [ ]

_____ the calculation is right, scientists can never be sure that they have included all variables and modeled them accurately

I didn’t go to the beach______ vacation. I stayed ______ home.

We can use it to chat with each other on theInternet.–Really Will you please show me _______ it

―Excuse me, Jim. Do you have any books about Chinese history―Yes. ______ book above the shelf is _______ useful one.