It is written clearly in the requirements that all passengers _______ check onto board thirty minutes before the plane takes off．

The new CEO asked that all inter-office communications ______ in writing rather than in person, ______ possible.

The World Wide Web is sometimes jokingly called the World Wide Wait because it ________ be very slow.   

 Look! If we had begun to do the work yesterday morning, we _______ ourselves just like them．

---Tom, _____we go home together this afternoon ? ---Ok !