You have to be accurate in this job,because a small mistake can make a big ________.
The experiment shows that proper amounts of exercise, if ________ regularly, can improve our health.
________ from the top of the tower, the south foot of the mountain is a sea of trees.
________ at my classmates' faces, 1 read the same excitement in their eyes.
Though ________ to see us, the professor gave us a warm welcome,
The first snow didn't fall until February in our province this year,__________ was unexpected.