18. Mr John doesn't wear glasses. He is over sixty.

→  In spite of being over sixty (hoặc in spite of his age), Mr John doesn't wear glasses.

19. he had much experience in machinery. He didn't succeed in repairing this machine.
→Despite his/having much experience in machinery, hee didn't succeed in repairing this machine.

20. We did the test well. It was difficult.
→ In spite of its difficulty, we did the test well.

21. He studied very well. His life was hard at that time.
→ Although his life was hard at that time, he studied very well.
22. The weather is bad. We are going to have a picnic
→  Though the weather is bad, we are going to have a picnic
23. He had not finished the essay. He went to sleep.
→ Although he had not finished the essay, he went to sleep.
24. He often tells lie. Many people believe him.
→ Though he often tells lie, many people believe him. 
25. He had taken any kinds of exercises.He got fatter and fatter.
→ Althoug he had taken any kinds of exercises, he got fatter and fatter.

18→  In spite of being over sixty (hoặc in spite of his age), Mr John doesn't wear glasses..
→Despite his/having much experience in machinery, hee didn't succeed in repairing this machine.

20.
→ In spite of its difficulty, we did the test well.

21. 
→ Although his life was hard at that time, he studied very well.
22. 
→  Though the weather is bad, we are going to have a picnic
23. 
→ Although he had not finished the essay, he went to sleep.
24.
→ Though he often tells lie, many people believe him. 
25. 
→ Althoug he had taken any kinds of exercises, he got fatter and fatter.