其它
Which of the following groups has equivalent ratios? 
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$$A$$, $1$ to $5$ $$=\frac{1}{5}$$, $$\frac{0.5}{1}=\frac{5}{10}=\frac{1}{2}$$, so wrong.  $$B$$, $$\frac{1}{5}=1:5$$, so true.  $$C$$, $5$ to $10$ $$=\frac{5}{10}=\frac{1}{2}$$, so wrong.  $$D$$, $$1:5=\frac{1}{5}$$, $$\frac{5}{10}=\frac{1}{2}$$, so wrong. 