We should do what we can to save those _____ species, including the tiger, an animal which was considered _____ to humans.
| A．dangerous; endangered | B．dangerous; in danger |
| C．endangered; in danger | D．endangered; dangerous |
In my opinion, life in the twenty-first century is much easier than ___________.
| A．that used to be | B．it is used to |
| C．it was used to | D．it used to be |
The field research will take Joan and Paul about five months; it will be a long time _________ we meet them again.
| A．after | B．before | C．since | D．when |
— I phoned you yesterday morning. A girl answered, but I didn’t recognize the voice.
— Oh, it __________ my younger sister. She was in my room at that moment.
| A．must have been | B．should have been |
| C．could have been | D．may have been |
He _______ Alice for ten years.
| A．married to | B．has married to |
| C．has married | D．has been married to |
He hesitated for a moment before kicking the ball, otherwise he ______ a goal.
| A．had scored | B．scored |
| C．would score | D．would have scored |