Have you ever been to theSports Center ____ is just opened in town?—No, notyet.[ ]

______ do you like the trip to Wuhan?－It’s wonderful.

We can’t go home _____ the heavy rain and we have to wait _____it stops.[ ]

The water in the river nearby will be dirtier than before if nothing __________.

I saw him ________ the supermarket just now.