--_________ to the United States?
--No, never, but I went to Canada a few years ago.
| A．Have you been | B．Have you gone |
| C．Did you go | D．Will you go |
It's________ far_______ walk home from here. Let's take a bus.
| A．so; that | B．too; to |
| C．enough; to | D．such; that |
They really don’t know how _________ the difficult problem.
| A．to solve | B．solve |
| C．solves | D．solved |
They used to be friends, ______?
| A．don’t they | B．didn’t they |
| C．do they | D．did they |
It has been many years ________ we met at the train station in 2008.
| A．when | B．after |
| C．before | D．since |