31. The cheering went on for quite some time _____ it died down and people took their seats again.
I know he hasn’t finished his homework, but ______, he has done his best.
We always keep ______ spare paper, in case we run out.
—I have studied growing plants as one of my interests. Could I make some suggestions? —______.
________ recent developments we do not think your scheme is practical.
Science and technology have __________ in important ways to the improvement of agricutural production.