Comments on "Attainable conditions and exact invariant for the   time-dependent harmonic oscillator"
  We make remarks on Fern\'{a}ndez Guasti's paper [{\it J. Phys. A: Math. Gen.} 39 (2006) 11825-11832] by pointing out some mistakes Fern\'{a}ndez Guasti derived therein. 
Kwang-Hua W. Chu