All _____ can be done has already been done.
| A．/ | B．what | C．that | D．which |
After visiting the harbor in the bay, they took a tour around the downtown area, ______ they visited many art galleries, shopping centers and had their lunch in a restaurant that served fancy foods.
| A．which | B．as | C．where | D．what |
Canada is the only country that _____ an entire continent in the world, facing the Atlantic ____ the east.
| A．makes up; on | B．covers; on | C．takes up; to | D．do up; in |
—I am afraid I can’t return the book to you before Friday.
—________.
| A．Don’t be afraid | B．Be careful |
| C．Not at all | D．Take your time |
—Does he often ask you for help?
—Oh，no，only________.
| A．all the time | B．at one time |
| C．at a time | D．at times |
________， I lost heart in English learning，but my teacher often said to me，“Keep on studying hard，and you’ll succeed________.”
| A．At a time；in time |
| B．At a time；on time |
| C．At one time；in time |
| D．At one time；on time |