What ____ heavy rain it was! —Yes, but I love _____ air after it rains. It smells so fresh.

an I operate this machine—Well, just refer to the _______.

To improve the quality of our products, we asked anyone ____________ had used the products for suggestions.

The policeman havefined me for speeding but finally，he let me go.

Who teaches______singing—Nobody, I learn it by_______.