---Alice’s second-hand computer ____ wrong although she used it only once.---You’d better go to check it.
I admire my English teacher. I can remember very few occasions ________ she stopped working because of ill health.
—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.