The time and effort he has devoted during the past few years _____ trees in that village are now considered to be very important.
34. It’s reported that in the past 50 years around 80 percent of Beijing’s courtyard houses ______.
33. If I_________you would drop in, I would have stayed home waiting for you.
32. ––When will you be back, Peter?––________a couple of days.
31. All books ______ to the library more than three days late will be subject to a fine.
30. When he was only thirty years old, he had already experienced______most people only experience when they are much older.