1.A group of young people are going to put up a tent at the foot of the hill.
2.How about take physical exercises in two hours' time （或：in two hours）?
3.The girls were present at the party with having their colorful dresses on.
4.That medicine has a good effect on you.Have it three times a day.
5.We can't rely on others' help.We ought to help each other.
6.Tom happened to be there when the fire took place.