Scientists also have no idea how long it will be before all wild animals in the cages _____.
| A．should be set free | B．will be set free | C．are set free | D．would be set free |
It is difficult to tell exactly ____ the saying began, but it is probable that it was in the theater or movie industry.
| A．where | B．when | C．why | D．that |
—Can you get me some of the novels?
—By all means. All but one of them ____ in our company.
| A．published | B．was published | C．were published | D．had been published |
—Why are so many northern Chinese visiting Southeast Asia countries recently ?
—They are trying to get a ___shelter from the cold weather in winter.
| A．magic | B．reliable | C．permanent | D．Temporary |
The story showed marriage between people of different races ,_____ was against the law at that time.
| A．who | B．which | C．whoever | D．whichever |
Getting your students ___ in classroom activities is vitally important.
| A．trapped | B．devoted | C．stuck | D．involved |