这都是心理和情感上的斗争，而不是算术上的加减乘除。
These are psychological and emotional battles, not battles about math.
算术上的第二项进展是加速算术运算的机械装置和机器的发明。
The next development in arithmetic was the invention of mechanical devices and machines to speed up the execution of arithmetic processes.
这种物质并不能改善他们在计算上的表现，但是算术上的提高可能是因为他们年轻健康。
The supplements did not improve their performance in tests of their mental arithmetic, but this may have been because they were young and healthy.
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