____ three times in a row, the boxer decided to give up fighting.
| A．Having defeated | B．To have defeated | C．Having been defeated | D．To have been defeated |
Bad habits, ______ formed(形成), are difficult to give up.
| A．and | B．once | C．for | D．but |
These natural parks are very important for preserving many animals, which would ______ run the risk of becoming extinct(灭绝的)．
| A．otherwise | B．other than | C．therefore | D．in another way |
The girl didn’t know who ______ for the broken vase.
| A．will be blamed | B．blamed | C．was to blame | D．blames |
______ with the size of the whole earth, the highest mountain does not seem high at all.
| A．When compared | B．While comparing |
| C．Compare | D．Comparing |
-- How long do you think it will be ______ the bus arrives here?
-- No more than five minutes.
| A．when | B．before | C．since | D．after |