In fact, my original intention is to insert a quick time stamp while I am editing MS Word documents. However, "Alt-Shift-T/Alt-Shift-D" method inserts a dynamic time stamp: the inserted object is in fact a variable, and get updated every time I save that document.
That is, when I save the Word document, all such time stamps become exactly the time I save the file. Of course, this is not very desirable to me.
I researched again in Google, and found this page.
Insert The Current Date to Word – Statically, Not as an Updating field | ProductiveWise
The keyboard shortcut for inserting the current date into a Word Document is ALT+SHIFT+D. The problem is that the inserted date is a live filed, so it is being updated every time you open the document.
To insert the current date without it ever being updated (that is, to insert the current date as simple text) – press CTRL+SHIFT+F9 when the cursor is inside the added field.
Conclusion
Use "Alt-Shift-T, then Left Arrow, then "Ctrl-Shift-F9", to insert a time stamp about time. Use "Alt-Shift-D, then Left Arrow, then "Ctrl-Shift-F9", to insert a time stamp about date.
(Quite ugly to me! Can anyone teach me shorter ways to insert such static time stamps in MS Word? I really appreciate that!)