Explanation:
1) at exactly 3:00 pm, I met with Mrs. Thompson.
2)At night, we watched fireflies in the backyard.
3) after excercises, everyone swam in the water
4) during the night, the horse ran off
5) for the first few weeks, the education of a puppy may be difficult
6) on sunday afternoon, i read the newspaper
7) after the field trip, everyone wrote a report.
8) after six weeks of training, andrea began a new job.
maybe no commas, but you get the point.
