_____ is known to all is that effective measures should be taken to deal with the problem of the over-exploiting of our resources.
The manager came over and asked the customer how ___________.
-Are you sure you have to? It’s been very late. -I don’t know ________ I can do it if not now.
Is it the letter you got yesterday ________ makes you so sad?
It’s important to listen to your teacher carefully in class, so try not to let your mind _________.
-Do you mind if I turn off the TV?-__________.