— They are said to have been familiar with each other.— But they_________. They were introduced only hours ago.
. It's reported that in the past 50 years around 80 percent of Beijing's courtyard houses ___________.
. If I ___________ you would drop in, I would have stayed home waiting for you.
. —When will you be back, Peter? —___________ a couple of days.
. . All books ___________ to the library more than three days late will be subject to a fine.
. When he was only thirty years old, he had already experienced ___________ most people only experience when they are much older.