18.
2. No, I didn't have a picnic at a camp.
3. No, I didn't go fishing to the lake.
4. No, I didn't visit my granny yesterday.
19.
2. don't
3. didn't
4. didn't
5. didn't
20.
1. We went camping at the camp in sumer.
2. Peter went fishing on the lake.
3. Boys played ball games at the camp.
4. We sang campfire songs.
21.
1. I went to the camp last summer.
2. The boys didn't go fishing in summer.
3. You went roller-skating last August.
4. Did Jane cook tasty food last night?