___________you try to do something beyond what you have already mastered, you will never grow.
| A．Since | B．When | C．Though | D．Unless |
—How far can you run without stopping?
—________.I've never tried.
| A．Don't mention it | B．That's all right |
| C．I have no idea | D．Go ahead |
—Would you mind answering some questions on shopping habits?
—________.
| A．Yes，with great pleasure |
| B．No，I am afraid I can't make it |
| C．Yes，it is worth the time |
| D．No，as long as it doesn't take long |
Whatever he does，once he sets up a goal，he will start pursuing it without ________.
| A．hesitation | B．suggestion |
| C．discussion | D．decision |
As is well－known，the brain performs a very important ________，which controls the nerve system of the body.
| A．motion | B．action |
| C．function | D．fact |
—What do you think of the project put forward by the Blacks?
—Considering its real ________，it will be well worth putting into practice，I suppose.
| A．reward | B．prize | C．cost | D．value |