不可扣除的

It is a labor to task the faculties of a man — such problems of profit and loss, of interest, of tare and tret,(8) and gauging of all kinds in it, as demand a universal knowledge.

这真是辛苦的劳役，考验人的全部官能，——这些赢利或损失的题，利息的题，扣除皮重的计算题，切都要确实数字，非得有全宇宙的知识不可啊。