They demanded that the books ______ to the school library right away.
| A．should return | B．be returned | C．were returned | D．returned |
The reason______ she failed to go to the party puzzled all of the people present.
| A．what | B．why | C．as | D．which |
In the U.S, ______a tip is thought to be polite when paying the bill.
| A．leave | B．having left | C．leaving | D．being left |
He is the only one of those clerks ________ to the important conference.
| A．who was inviting | B．who were invited |
| C．who has been invited | D．who have been invited. |
When I turned to Tony for help, I found that the more he tried to explain, ___________.
| A．the more I became confused. | B．the more confused became I |
| C．the more confused I became | D．I became more confused. |
The two boys share the same hobbies but they are quite different _______ personality.
| A．in | B．with | C．for | D．on |