lim [(3-x)/3]^(2/x)
= lim [(1-x/3)^(-3/x)]^(-2/3)
= e^(-2/3) = 1/e^(2/3).这个呢？x趋向与1+,（1+ln）的5/lnx次方lim (1+lnx)^(5/lnx)
= lim[ (1+lnx)^(1/lnx)]^5 = e^5