what is the keyword short cut for comment multiple lines in TestComplete?

There is no Keyboard shortcut perticulary.

Option1: Select the lines whihc you want to comment out and click on the Multiline comment symbol on the TestComplete dashboard.

Option2: You can create your own keyboard short cut.

Step1: Go to Tools-->Customize Keyboard

Step2: Select Comment from Categories and create shortcut keys as your wish. then Save