--- The research on the new flu virus vaccine is challenging and demanding. Who do you think can do the job? --- ____ my students have a try?
Ten years ago, the population of our village was ______ that of theirs.
She has been working hard day and night, which of course, _______ her pale face.
--- Are you satisfied with what he did? --- No. It couldn’t have been ______.
--- He worked out such different questions at a very young age. --- Oh, he ______ a very smart student then.
In our childhood, we were often ______ by Grandma to pay attention to our table manners.