Here are the correct answers for the blanks in the text:

21. **D. improve**
22. **C. Finally**
23. **B. slides**
24. **C. speak**
25. **B. at**
26. **A. with**

So the completed sentence would read:

"I hope you want to **improve** your presentation skills, and I thought I’d share some tips that helped me. Use simple fonts and avoid too much text. Include pictures or charts to make your ideas clearer. Next, practice your delivery to sound confident. Also, focus on your **slides**. Make eye contact with 5-6 people, but don’t stare at one person too long. Use natural hand gestures to emphasize your points. When presenting, **speak** deeply if you feel nervous. This helps you speak clearly and maintain a calm tone of voice. Remember to engage **at** your audience by asking questions or making your presentation interactive. Lastly, if you don’t know an answer during Q&A, be honest and **with** professional."