Have you been to the Great Wall?－Perhaps not in my memory. _______ , it might have been during my early childhood.

The poor little boy often stands _____ the gate. He is waiting for his mother. [ ]

Can I have some more ice cream, Mum ? —Sorry. There is ______ left in the fridge.

If you don’t pay your electricity bill, it will be _______.

He will send me an e-mail as soon as he _____ in America.