—Have you found out anything, sir?—We are sure that the thief entered the house through the window instead of breaking in. You have closed the window before you left.
As is known to all language learners, newly learnt words will soon be forgotten unless ______ used in everyday communication.
Many students listened to the lecture, but I wondered how much they ______.
I think that something has to be done to stop the air from being polluted, ______ ?
It has been reported that some government leaders ______ their authority and position to get illegal profits for themselves.
Let's learn to use the problem we are facing ______ a stepping-stone to future success.