. It is on thing to accuse a person of a certain crime, but ________.
| A．to prove it is quite another matter | B．proving it is difficult |
| C．it is hard to prove | D．how to prove is difficult |
The room was so quiet that she could hear the _____ of her heart.
| A．hitting | B．beating | C．tapping | D．knocking |
The new safety regulations were agreed on after _____ with the work-force.
| A．conference | B．participation |
| C．intervention | D．consultation |
His test results are not very _____. He does well one week and badly the next.
| A．invariable | B．consequent | C．continuous | D．consistent |
Scientists think they have _____ in their attempt to find the causes of some major dieases.
| A．broken through | B．worked out |
| C．fallen out | D．got round |
If you ever have the _____ to go abroad to work, you should take it.
| A．possibility | B．offer | C．luck | D．chance |