--- Have you really been to visit the Bird’s Nest in Beijing? ---- I ______ it last summer vacation.
—Beijing experienced _____ heaviest snowfall in ____ month of January .
We already have ______pencils, but we need two ____ pens.
Why are you leaving right now? You promised to stay ____ hours.
We asked John and Jerry, but ____ of them could offer a satisfactory explanation.
This book______18 articles , _______ three written by my father.