Hi @李 家輝
On my test environment with Office 2016 Professional Plus installed, I found I can enter characters in Bing Image Search box.
Please try to enter some text and search it, and choose "Word offline" as following image.
Then you may browse and insert the image.
The steps above are my test results, it works as a workaround. I will continue to research this issue, any updates I will share with you.
Thanks for your understanding.
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment". Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.