Is _______ necessary_______ the workers wear uniforms at work?A. it, for B. this, to C. it, that
________is helpful to our environment.
We ________ cross the street until the traffic lights turn green.
You look too tired. Why not ________ a rest?
Let's ________ the TV to watch the news program.
—Is the wine made ________ wheat?—Yes, it is made ________ China.