Here's a step-by-step guide to solving the questions from your English test:

### Multiple Choice Answers:
26. The natural disaster that is NOT mentioned in the text is:
- **C. a tornado**

27. The answer to “What is his/ her unforgettable personal experience?” is:
- **A. the strangeness of nature**

28. What did NOT happen during the time of the London Killer Fog?
- **C. pollution**

29. The traffic stopped because of:
- **A. the heavy fog**

30. How long did the London Killer Fog last?
- **A. for six days**

### Section Writing:
31. Find the mistake in each sentence:
- **Correction:** "I asked her if she believes in the existence of UFOs."

32. Rewrite the sentence as directed:
- **Correction:** "She is looking forward to seeing her grandparents again soon."

### Rewriting Sentences:
33. "I will give him your letter when I see him tomorrow."
- **Rewritten:** "As soon as I see him, I will give him your letter."

34. "These are their new rooms."
- **Rewritten:** "These new rooms are theirs."

35. Minh said that he would send his email to the teacher the next day.
- **Rewritten:** "Minh said that he would send his email to the teacher the next day."

### Writing Paragraph about the Advantages of Email:
Here’s a sample paragraph:

Email has transformed communication in modern life by offering numerous advantages. One key benefit is speed; with email, people can send and receive messages instantly without waiting for days for responses. Additionally, email allows for the use of simple and formal language, enabling quick, clear communications. It also reduces paper use, contributing to environmental sustainability. Using email, individuals can easily send birthday cards, share favorite pictures, and stay connected with family and friends efficiently. Overall, email is an essential tool for maintaining relationships in today’s fast-paced world.

Feel free to adjust the writing section as needed!