Hi there! As you have posted multiple sentences, you need to say: 'Are these sentences correct?'
I have corrected the grammar foryou:
1. Certain people allow teenagers to smoke on the road
2. To do nothing is to do ill
3. Avoid making promises you can't keep (eg don't make promises that you will not keep because they are too dangerous)
4. He stopped surfing the internet
5. He stopped to surf the internet
6. When I opened my eyes, I discovered that I had lost my phone
7. I sometimes I feel like I live to eat
8. He is too shy to speak to strangers (Correct!)