It____ Tom that parked the car here, as he is the only one with a car.
| A．may be | B．can be | C．must have been | D．should have been |
38.The task is hard, ___, the workers managed to finish it in time.
| A．therefore | B．otherwise | C．however | D．yet |
39.When you read the book, you’d better made a mark ____ you have any questions.
| A．at which | B．at where | C．place | D．where |
___ she will join us in the game is not decided yet.
| A．If | B．Whether | C．What | D．While |
There are many sports lovers in his office.Some love climbing, ___ others enjoy fishing.
| A．or | B．for | C．while | D．so |
They can surely overcome those difficulties ___ they are closely united.
| A．even if | B．as long as | C．so long as | D．B and C |