I was deep in thought, so I didn't notice _____.
—Can you give me some advice on what I said just now? —Sorry, my mind _____.
I’d appreciate _____ if you would like to teach me how to use the computer.
The government has to close those small factories to prevent the water of the river ______.
There are _____ products to be sold in the factory store. Which of the following is not correct?
He did not regret saying what he did but felt that he _____ it differently.