Over the years, people have learned from ants that teamwork and perseverance are indeed two key ______ to success.
| A．certificates | B．ingredients |
| C．approaches | D．instructions |
It was playing computer games ____ cost the boy plenty of time ____ he ought to have spent doing his lessons.
| A．what; that | B．that; when | C．which; that | D．that; that |
We _____ live in a small flat but last year we bought a house.
| A．would | B．had to | C．used to | D．ought to |
All these gifts must be mailed immediately_________ in time for Christmas.
| A．in order to have received | B．in order to receive |
| C．so as to be received | D．so as to be receiving |
------Excuse me, sir, where is Room 301?
----- Just a minute, I’ll have Bob_______ you to your room.
| A．show | B．shows | C．to show | D．showing |
I prefer a flat in Inverness to _________ in Perth, because I want to live near my mom’s.
| A．one | B．that | C．it | D．this |