David is________than his brother.So he always makes more mistakes.
I discovered that listening to ______is the secret ______language learning.
The students don’t know the broken computer.
I don’t know if Mr. Smith ____. If he ___, I will tell you.
He used to __ in a small village, but now he has been used to __ in the big city.
— Could you tell me ______?— Certainly. In half an hour.