The students are ______ to hand in the exercises before class.
—Did you know more about the mine accident? —Oh,sorry,I had no idea. I ________ the Rescue Center now.
—________ you interrupt now? Can't you see I'm on the phone? —Sorry Sir, but it's urgent.
As is reported, it will be more than 20 years ________ humans are able to walk on Mars.
Be careful that a good name of a product doesn't ________ mean good quality of it.
The supermarket rules state that no goods ________ be taken out of the supermarket, ________ paid for by the shopper.