Timespan to srting format?

Hi,
How to convert timespan value to string format?
05.03:02:05
Convert to ?
05 days, 03 hr 02 min 05 sec
I did try string.format("{0} days ,{1} hr , {2} min ,{3} sec", t.Days,t.Hours,t.Minutes,t.Seconds);
but it removes all '0' and shows 5 days 3 hr 2 min 5sec.
How to maintain double digit?