Looks fine, except I would put "undefined" for the first 10ns of C', "undefined" for the first 20ns of AB, and "undefined" for the first 40ns of F. (Unless they gave you initial input conditions at t-40ns, of course!)
I'll add another "looks fine" and second the recommendation to start each of the signals in an unknown state (often indicated by a line that is halfway between the two levels).