My father painted the picture last week

----> The picture was painted by my father last week

They will buy a new bike in the next days

-----> A new bike will be bought in the next days
3. If you don't study hard, you won't pass the exam.
4. If the water is contaminated, people will get more diseaseases.
5. A mid-term examination is being done now
6.If there wasn't so much light in the city at night, we could see the stars clearly.