.Pens are used for on paper.
This backpack is not expensive. And the price of it is the ____of the three.
The weather in Guiyang in summer is ___than that in DuYun.. They are different.
_________ it is snowing, _________ they are still working.
---_______does your mother watch the talk show?---Once a week.
It’s_____ black. It’ s ____ black ruler.