Ⅰ、1、at, in
2、with, in
3、by, on
4、at
5、about
Ⅱ、1、were having , heard
2、were, when, was taken down
3、was playing , came in
4、woke up , was rising
5、while , was doing
Ⅲ、One possible version:
Yesterday was a sunny weekend. Many people were in the park. They were all
enjoying themselves.Two girls were riding bikes.Two old women were walking along
the river ,and they were very happy. A boy was reading a book on the grass. Two men
were fishing. A lovely baby was sleeping near them.