Without a shadow of a doubt is a common expression which means you are 100% certain you are correct about something.
For example, without a shadow of a doubt learning English is hard work.
On a personal note, without a shadow of a doubt, the most valuable things in my life are my friends and family, my health, my Apple Nano and my trainers.
Furthermore, without a shadow of a doubt, the Molotov Dukebox gig I went to last Friday night was one of my 2014 highlights. 
Did I paint the town red? Did I have a blast? Did I have a hangover? Yep, yep and yep.
Janette was in the crowd jumping around like a kid in a sweet shop! Thank you Molotov Dukebox, you were awesome!!!!
So, what are you certain about? Without a shadow of a doubt what, or who are the most important things in your life?
