In the afternoon, Dr Zhang walks in space.

下午，张博士在太空漫步。

youdao

Goodbye, Dr Zhang. I hope you have a good journey back to Guangzhou.

再见，张博士。我希望你有个好的旅途回广州。

youdao

Dr Zhang Ling is a scientist. She works in the space station. What does she do every day?

张玲博士是一个科学家。她在太空站工作。她每天都做些什么呢？

youdao

Zhang's surgeon is Dr.Samuel So, director of the Stanford University Asian Liver Center.

VOA: standard.2010.07.26

If so, then why did all his reference letters call him Mr. Zhang, not Dr. Zhang?

CNN: ASIANOW - TIME Asia | Young China | Tips From an Expert