He made another wonderful discovery, _______ of great importance to science.
| A．which I think is | B．which I think it |
| C．which I think it is | D．I think which is |
If you pay for the computer in cash, you could have a 5% discount; _______ we can deliver it to you for free.
| A．in demand | B．in addition | C．in return | D．in place |
The project ______ last month but unfortunately it had to be prolonged because of the financial problem.
| A．needn’t have been finished | B．shouldn’t have finished |
C．could have been finished | D．must have finished |
I think this software is of little use to your work. It is really a ________ of money.
| A．lack | B．load | C．question | D．waste |
It’s said that this kind of plant only gives off this strange perfume on ________ conditions which the scientists are trying to figure out now.
| A．outstanding | B．certain | C．obvious | D．ordinary |
As we know, success often comes after ______ failure; so don’t be so upset about _______ failure of this matter.
| A．a; a | B．不填; the |
C．a; the | D．不填; a |