In our class, when the bell rang and the teacher closed his book, it was a ______ for everyone to stand up.
Finally, I bought the new book,____I spent twenty yuan in the bookstore where my old friend Was the boss.
The Crime wave is one of the biggest problems _______ the new government is now faced.
The two astronauts said they would never forget the days ____they worked together in the Spaceship and the days ______.they spent together.
Alex asked the policeman_______ he worked to contact him Whenever there was an accident.
I will never forget the day _______ I joined theLeague.