In order to assure results correctness the requirement for system is that friction wearofmetal pairs must be a little, even omitted.
测量系统要求金属配副磨损量应很小,甚至可以忽略,以确保结果的准确性。
2
The feather went out with the introduction of a metal nib which was an improvement because skritching along with a feather tended to wear it out pretty quickly.