Here are the rewritten sentences using the given linking words and phrases:
1. We switched off the lights before we went to bed. → Having switched off the lights, we went to bed.
2. The boy asked his mother’s permission and then went out to play. → Having asked his mother's permission, the boy went out to play.
3. As he had drunk too much, he didn’t drive home himself. → Having drunk too much, he didn't drive home himself.
4. We have done two tests today, so we are exhausted. → Having done two tests today, we are exhausted.
5. She filled the washing machine and switched it on. → Having filled the washing machine, she switched it on.
6. She had been to disco the night before and she overslept in the morning. → Having been to disco the night before, she overslept in the morning.
7. We had worked in the garden all day and were sunburned in the evening. → Having worked in the garden all day, we were sunburned in the evening.
8. She had not slept for two days and therefore she wasn’t able to concentrate. → Not having slept for two days, she wasn’t able to concentrate.
9. Since Sarah had not seen him for ages, Sarah didn’t recognize him. → Not having seen him for ages, Sarah didn’t recognize him.
10. I had not ridden a horse for a long time and I found it very difficult to keep in the saddle. → Not having ridden a horse for a long time, I found it very difficult to keep in the saddle.
11. I went to bed. I was very tired. → I went to bed because I was very tired.
12. Many people avoid using a microwave oven for fear of its rays. It has been shown to be safe. → Although many people avoid using a microwave oven for fear of its rays, it has been shown to be safe.
13. Because of his age, Mr. Jones was not hired. He had the necessary qualifications. → Even though he had the necessary qualifications, Mr. Jones was not hired because of his age.
14. It is warm and sunny today. We go to the park. → We go to the park because it is warm and sunny today.
15. Nick seems to be a trustworthy person. I don't ask him for any advice before making important decisions. → However, I don't ask Nick for any advice before making important decisions, although he seems to be a trustworthy person.
16. Many teenagers are victims of cyberbullying. As a result, they become depressed. → Many teenagers are victims of cyberbullying because of which they become depressed.
17. Our awareness campaign was a success. However, we still need to do more to stop cyberbullying. → Our awareness campaign was a success, although we still need to do more to stop cyberbullying.
18. The forest has become a nature reserve. Therefore, people are not allowed to camp or hunt there. → Since the forest has become a nature reserve, people are not allowed to camp or hunt there.
19. There have been many campaigns to end deforestation. But trees are still being cut down. → In spite of many campaigns to end deforestation, trees are still being cut down.
20. There was peer pressure from my friends. However, I didn't skip lessons. → Despite peer pressure from my friends, I didn't skip lessons.
21. Mandy is doing environmental projects. She is also helping teenagers find part-time jobs. → In addition to doing environmental projects, Mandy is helping teenagers find part-time jobs.
22. We made an effort to save our local park. But it was sold to a property developer. → Despite making an effort to save our local park, it was sold to a property developer.
23. Because there is an increase in cyberbullying, many schools have to update their anti-bullying policies. → Because of the increase in cyberbullying, many schools have to update their anti-bullying policies.
24. Although the police are using new methods to control crime in the city, crime figures are still high. → Despite using new methods to control crime in the city, crime figures are still high.
25. Many teenagers have to deal with physical bullying. They also have to deal with cyberbullying. → In addition to physical bullying, many teenagers have to deal with cyberbullying.
26. Many teenagers are afraid or not sure if they are bullied or not, so they don’t do anything about their situation. → Many teenagers are afraid or not sure if they are bullied or not. Therefore, they don’t do anything about their situation.
27. In spite of developing health problems, some people continue to drink too much. → Although they develop health problems, some people continue to drink too much.
28. Because of test anxiety, some students suffer from stress and fail to do well in their exams. → Because they suffer from test anxiety, some students fail to do well in their exams.
29. I’m getting anxious about my English exam, and I don’t think I have enough time to revise for it. → I’m getting anxious about my English exam. Besides, I don’t think I have enough time to revise for it.
30. The Internet is a great source of information, but it may not be reliable. → The Internet is a great source of information. However, it may not be reliable.