The dog is very ___, and it can work out the problem____.

I go to school by _______, but my best friend goes there ______foot. 

 Now , some robots are __________ to do the same things ____________ people.

—Yesterday I lost my pen.  I couldn’t find_______. —Oh, it’s a pity. You’d better buy ________ this afternoon.

If there aren’t so many cars, our air would be much ____.