1. People throw rubbish in the street. The street doesn't look attractive.
If people didn't throw rubbish in the street, the street would look attractive.
2. There are so many billboard in our city. People cannot enjoy the view.
If there weren't so many billboard in our city, people could enjoy the view.
3. She has a headache after work every day. She works in a noisy office.
She wouldn't have a headache after work every day if she didn't work in a noisy office.
4. The karaoke bar makes so much noise almost every night. The residents complain to its owner.
If the karaoke bar didn't make so much noise almost every night, the residents wouldn't complain to its owner.
5. We turn on the heater all the time. We have to pay three million dong for electricity a month.
We wouldn't have to pay three million dong for electricity a month if we didn't turn on the heater all the time.
6. There is so much light in the city at night. We can not see the stars clearly.
We could see the stars clearly if there weren't so much light in the city at night.