With all the food supply ___, the researchers had to put an end to the wildlife protection project and returned home.
| A．running out | B．to use up | C．run out of | D．using up |
Where _______ for the past few years？
| A．are you | B．have you been | C．have you gone | D．did you go |
I find the story really worth ______.
| A．reading | B．to read | C．being read | D．to be read |
I will never forget the day _____ we spend together.
| A．when | B．on that | C．which | D．While |
I will never forget the day _____ we worked together in London.
| A．when | B．on that | C．which | D．while |
________ your letter, I would have started off two days ago.
| A．If I received | B．Should I receive |
| C．If I could have received | D．Had I received |