6.
1.doing 2. with 3. fall down 4. off 5.burn 6. ride
7.scratch 8. dangerous
7.
1. Why shouldn't I climb that tree ?
2. Is Nga going to run down the stairs ?
3. Don't play with the neighbor's cat because it may scratch you.
4. Why shouldn't your sister ride her bike too fast?
5. You should wear a helmet when you ride your motorbike.
6. She shouldn't jump into the lake because she may drown.
7. He fall off his bike and broke his leg.