The people who objected to cloning human beings went on strike and _________ the traffic.
At the meeting they discussed three different ________ to the study of physics.
Our manager has gone to Paris, so I have to deal with all the letters during his ________.
To qualify yourself for this kind of new job, I recommend that you ________ some online courses.
I soon found that the work I was doing had already been done by someone else —________ I was wasting time.
The doctor has worked with patients of this kind for eight years, so he knows what ________ in his job.