求解一道阅读句子插入题，谢谢！

MD100UID: 3313921

[  ] The spurt of growth stimulated by the war positioned the American pottery industry for a qualitative change as well. [  ] During the nineteenth century, the output of American pottery makers went through an evolution of sorts. This was made possible by technical advancement as well as by market conditions. As the availability of kilns that could reach the higher temperatures needed to create the high-fired stoneware improved, experiments revealed that the same clay used to produce low-fired red ware could produce a stronger, lighter-colored type of pottery if fired at a hotter temperature. [  ] What resulted was a third variety known as yellow ware. Basically an evolutionary improvement on red ware that was used largely for more functional and affordable mass-market items, yellow ware was soon to be eclipsed by yet another development; this one known as Rockingham ware.

为什么不能够插入到第二个空呢？

秋雨荆州UID: 2903781

as句后面在介绍technical advancement