—Why didn’t you answer my phone call, Jack?—I’m sorry, but I ________ then.
---Do you think people can live on the moon one day? ---May be. However, it may take ________ years to make it.
Ask your brother to call me if he ______ back tomorrow.
--Would you please tell me________this DV? --Yes.It’s very easy.
Jack’s mother wondered_________.
The mountain was ________ high _________few people in our city reached the top.