铜$\rm (I)$、乙腈$\rm ($简写为$\rm L)$的某水溶液体系中含铜物种的分布曲线如图。纵坐标$\rm (\delta)$为含铜物种占总铜的物质的量分数，总铜浓度为$1.0\times {{10}^{-3}}\text{ mol}\cdot {{\text{L}}^{-1}}$。下列描述正确的是$(\quad\ \ \ \ )$

$\\text{C}{{\\text{u}}^{+}}+3\\text{L}\\rightleftharpoons {{\\left[ \\text{Cu}{{\\text{L}}_{3}} \\right]}^{+}}$的$\\lg K=0.27$

当$c\\left( \\text{C}{{\\text{u}}^{+}} \\right)=c\\left\\{ {{[\\text{CuL}]}^{+}} \\right\\}$时，$c\\left\\{ {{\\left[ \\text{Cu}{{\\text{L}}_{2}} \\right]}^{+}} \\right\\}=2.0\\times {{10}^{-4}}\\text{ mol}\\cdot {{\\text{L}}^{-1}}$

$n$从$\\rm 0$增加到$\\rm 2$，${{\\left[ \\text{Cu}{{\\text{L}}_{n}} \\right]}^{+}}$结合$\\rm L$的能力随之减小

若$c\\left\\{ {{[\\text{CuL}]}^{+}} \\right\\}=c\\left\\{ {{\\left[ \\text{Cu}{{\\text{L}}_{3}} \\right]}^{+}} \\right\\}$，则$2c\\left\\{ {{\\left[ \\text{Cu}{{\\text{L}}_{2}} \\right]}^{+}} \\right\\}\\lt c\\left\\{ {{[\\text{CuL}]}^{+}} \\right\\}+3c\\left\\{ {{\\left[ \\text{Cu}{{\\text{L}}_{3}} \\right]}^{+}} \\right\\}$

$\rm A$．$\text{C}{{\text{u}}^{+}}+3\text{L}\rightleftharpoons {{\left[ \text{Cu}{{\text{L}}_{3}} \right]}^{+}}$的$K=\dfrac{c\left\{ {{\left[ \text{Cu}{{\text{L}}_{3}} \right]}^{+}} \right\}}{c\left( \text{C}{{\text{u}}^{+}} \right)\times {{c}^{3}}\left( \text{L} \right)}$，当图中$\delta \left\{ {{\left[ \text{Cu}{{\text{L}}_{3}} \right]}^{+}} \right\}=\delta \left( \text{C}{{\text{u}}^{+}} \right)$时，$K=\dfrac{1}{{{c}^{3}}\left( \text{L} \right)}$，$\text{lg}K=-3\text{lg}c\left( \text{L} \right)$，由图像可知，此时$-1.6\lt \text{lg}c\left( \text{L} \right)\lt -1.2$，则$\text{lg}K\rm ≠0.27$，$\rm A$错误；

$\rm B$．当$c\left( \text{C}{{\text{u}}^{+}} \right)=c\left\{ {{[\text{CuL}]}^{+}} \right\}$时，由图像可知，$\delta \left( \text{C}{{\text{u}}^{+}} \right)=\delta \left\{ {{\left[ \text{CuL} \right]}^{+}} \right\}=0.48$，$\delta \left\{ {{\left[ \text{Cu}{{\text{L}}_{3}} \right]}^{+}} \right\}$可忽略不计，则，$\delta \left\{ {{\left[ \text{Cu}{{\text{L}}_{2}} \right]}^{+}} \right\}=0.04$，$c\left\{ {{\left[ \text{Cu}{{\text{L}}_{2}} \right]}^{+}} \right\}=0.04\times 1.0\times {{10}^{-3}}=4\times {{10}^{-5}}\text{ mol/L}$，$\rm B$错误；

$\rm C$．${{\left[ \text{Cu}{{\text{L}}_{n}} \right]}^{+}}$结合$\rm L$的离子方程式为${{\left[ \text{Cu}{{\text{L}}_{n}} \right]}^{+}}+\text{L}\rightleftharpoons {{\left[ \text{Cu}{{\text{L}}_{n+1}} \right]}^{+}}$，当$\delta \left\{ {{\left[ \text{Cu}{{\text{L}}_{n}} \right]}^{+}} \right\}=\delta \left\{ {{\left[ \text{Cu}{{\text{L}}_{n+1}} \right]}^{+}} \right\}$时，$K=\dfrac{1}{c\left( \text{L} \right)}$，由图像交点可知，随着$n$变大，$c\left( \text{L} \right)$逐渐变大，则$K$值变小，说明${{\left[ \text{Cu}{{\text{L}}_{n}} \right]}^{+}}$结合$\rm L$的能力随之减小，$\rm C$正确；

$\rm D$．若$c\left\{ {{[\text{CuL}]}^{+}} \right\}=c\left\{ {{\left[ \text{Cu}{{\text{L}}_{3}} \right]}^{+}} \right\}$，由图像交点可知，$\delta \left\{ {{\left[ \text{CuL} \right]}^{+}} \right\}=\delta \left\{ {{\left[ \text{Cu}{{\text{L}}_{3}} \right]}^{+}} \right\}\lt 0.2$，$\delta \left\{ {{\left[ \text{Cu}{{\text{L}}_{2}} \right]}^{+}} \right\}\gt 0.6$，则$c\left\{ {{\left[ \text{Cu}{{\text{L}}_{2}} \right]}^{+}} \right\}\gt 2c\left\{ {{\left[ \text{Cu}{{\text{L}}_{3}} \right]}^{+}} \right\}$，故$2c\left\{ {{\left[ \text{Cu}{{\text{L}}_{2}} \right]}^{+}} \right\}\gt c\left\{ {{\left[ \text{CuL} \right]}^{+}} \right\}+3c\left\{ {{\left[ \text{Cu}{{\text{L}}_{3}} \right]}^{+}} \right\}$，$\rm D$错误；

故选：$\rm C$