I was trying to use the following to send an excel file to someone
and it worked:

ActiveWorkbook.SendMail Recipients:="aaa@..."

I wonder, if I want to send to more than just one recipient, for
instance, if I also want to cc "bbb@...", how shall I write
the code?

I tried the following two but didn't work.

Recipients:="aaa@..." "bbb@..."
Recipients:="aaa@...","bbb@..."