. The book, _______ is blue, is mine.
| A．the cover of which | B．whose cover |
| C．of which the cover | D．all the above |
—Mr. Smith, I wonder if I could take Friday off?
— ______? It’s a bit difficult with so many people away on holiday, you know.
| A．How come | B．Is it necessary |
| C．Where are you going | D．Do you really have to |
After five days’ climbing in the mountain, they reached ____ they thought was the place they’d been dreaming of.
| A．that | B．where | C．which | D．what |
I’m moving to the countryside because the air there is much fresher than ____ in the city.
| A．ones | B．one | C．that | D．those |
--- Can I call for some friends and spend the day outside with them, Mom?
--- ____ I’ve told you to have a weekend on your own.
| A．Why so? | B．Why not? |
| C．How come? | D．So what? |
--- I hear Robert has gone to Harvard University for his master’s degree.
--- Oh, how nice! Do you know when he ____?
| A．was leaving | B．left | C．had left | D．has left |