________ from endless homework on weekends, the students now find their own activities, such as taking a ride together to watch the sunrise.
| A．Freed | B．Freeing | C．To free | D．Having freed |
At school, some students are active, ______ some are shy, yet they can be good friends with one another.
| A．while | B．although | C．since | D．thus |
___________ seems hard to believe is that the bird the officer uses is the same bird often seen in public parks----the pigeons.
| A．What | B．Whatever |
| C．Which | D．That |
I’d appreciate _______ if you could let me know in advance whether you will come or not.
| A．it | B．you | C．one | D．what |
It was after he had read the requirements _______ Mr. Black realized the task was too difficult to be finished.
| A．when | B．that | C．which | D．what |
The last bus _________ two minutes before I arrived at the bus stop. What a pity!
| A．left | B．has left |
| C．was leaving | D．had left |