Accumulation points on 3-fold canonical thresholds

We obtain that the nonzero accumulation points of the set of 3-fold canonical thresholds $\ct(X,S)$ are precisely $1/k$ where $k\ge 2$ is an integer and $S$ is an effective integral divisor of a projective 3-fold $X$ with only terminal singularities. Moreover, we generalize the ascending chain condition for the set of 3-fold canonical thresholds to pair.