"showing elapsed time and wall clock time correspondingly."
what‘s difference between elapsed time and wall time?
http://stackoverflow.com/questions/30267969/what-is-the-difference-between-clock-time-and-wall-time
Adolescence is an awkward, in-between age.
w/o: without
原文：http://www.cnblogs.com/jvava/p/5722403.html