MathmL中包含括号的分数

Question

如何使分数像第二个公式一样？

my sample formula

<math display="block" xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>D</mi><mi>e</mi></msub><mo>=</mo><mrow><mn>1</mn><mo>,</mo><mn>3</mn></mrow><mi>&middot;</mi><mfrac><mfenced><msup><mrow><mi>a</mi><mo>&middot;</mo><mi>b</mi></mrow><mn>0,625</mn></msup></mfenced><msup><mfenced><mrow><mi>a</mi><mo mathsize="small">+</mo><mi>b</mi></mrow></mfenced><mn>0,25</mn></msup></mfrac><mtext>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; [m]</mtext><mtext mathcolor="DodgerBlue"> &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; Formel 1.3</mtext> 
    </math> 

Answer 1

<math display="block" xmlns="http://www.w3.org/1998/Math/MathML"> 
<mrow> 
<msub><mi>D</mi><mi>e</mi></msub> 
<mo>=</mo> 
<mn>1,3</mn> 
<mo>.</mo> 
<mfrac> 
<mrow><mo stretchy="false" form="prefix">(</mo><mi>a</mi><mo>.</mo><mi>b</mi><msup><mo stretchy="false" form="postfix">)</mo><mn>0,625</mn></msup></mrow> 
<mrow><mo stretchy="false" form="prefix">(</mo><mi>a</mi><mo>+</mo><mi>b</mi><msup><mo stretchy="false" form="postfix">)</mo><mn>0,25</mn></msup></mrow> 
</mfrac> 
</mrow> 
</math>