As far as the length is concerned, there is no restriction.
His guidance helped me in all the time of research and writing of this thesis. I would like to extend.
Ying Wu for the continuous support of my Ph. You will see few dissertations and academic papers without an acknowledgement page. Without their care and funding, it was impossible to reach the goal. Keep writing a lot to refine your academic writing skills.
Do not make the same mistake!
For example, you can give special thanks to the laboratory assistants who were with you while you were carrying out your experiments. Example of acknowledgement in research paper - experienced.