I’ve listened to Professor Smith’s talk about medicine,but I still haven’t got a good understanding of its key _________.
The new safety regulations were agreed on after _____ with the work-force.
His test results are not very _____. He does well one week and badly the next.
Scientists think they have _____ in their attempt to find the causes of some major dieases.
If you ever have the _____ to go abroad to work, you should take it.
In aerospace devices the weight of the necessary power producing equipment is _____.