In the meantime, the question facing business is whether such research is ______ the costs.
— Do you know the old man ______ on the bench over there?— He is my grandfather.
If you don’t learn to think _____ you are young, you may never learn.
A new way of teaching _____ in the article can make learning easier.
My mother asked me where _____, and I told her that I was going to buy some food.
I still don’t know ______ she’s planning to come to my birthday party or not.