Why not leave the door _______? I think the air in the room smells bad.
| A．opening | B．opened | C．open | D．to open |
Don’t try to do everything at once. Take it a bit _______.
| A．at times | B．at that time |
| C．at all times | D．at a time |
—_______ they _______ the book _______ to the library yet?
—Yes, they have.
| A．Have; returned; / | B．Have; returned; back |
| C．Did; return; / | D．Did; return; back |
—Why are you looking for Mary in a hurry, John?
—The boss is wondering where she _______ and how long she _______ there.
| A．has been; has been | B．has gone; has gone |
| C．has been; has gone | D．has gone; has been |
It _______ over ten days since the dog _______.
| A．is; has been dead | B．has been; died |
| C．has been; has been dead | D．was; has died |