6.　　 I thought I would never forget this trip.

5.　　 We all felt very tired, but we were happy.

4.　　 We forgot the time. We didn’t come back until 5 o’clock.

3.　　 We enjoyed ourselves.

2.　　 I got up very early (late). After breakfast I went to …with my friends by bike, bus，…

1.　　 Last Sunday(Saturday,…) ,it was sunny(rainy, windy, foggy,)

2、　　　 旅游

7.　　 If everyone makes contribution to protecting the environment, the world will become much more beautiful.

6.　　 We must pick up some rubbish and throw it into a dustbin

5.　　 We should plant more flowers and trees.