As it is difficult to theoretically predict a propellant's burn rate with sufficient engineering accuracy, the only recourse is to measure burn rate utilizing any number of proven techniques.

因为它是难以从理论上预测推进剂的燃烧率有足够的工程精度，唯一的追索权是衡量烧伤率，利用任何数目的证明技巧。

youdao

Yet even he concedes that these carbon nanomaterials are so complex that it is difficult to predict their properties theoretically.

ECONOMIST: Space-age soot