— Jack, do you know the answer ______ this question? It’s too difficult for me. — Sorry, I don’t know. You can ask Jim for help. He is good at math.
--My aunt ______________ Singapore for a holiday. ---It’s a beautiful country. I ___________there twice.
Look! __________ high speed the roller coaster is __________.
What will the computer ______ in the future?
Father put the ladder(梯子)_________ the tree to pick the apples for me.
book named Harry Potter is good friend of mine.