A twelfth part of the labour of making a plough is an appreciable quantity .
制犁劳动的十二分之一还是－可觉察的数量。
Space debris made news on March twelfth when a part of an old rocket motor about ten centimeters in size threatened the International Space Station .
空间碎片在三月二十日那天就制造了一个新闻：一个大约十厘米大小的旧火箭马达威胁着国际空间站。
twelfth part