I think the idea of a stock must have been invented independently at many times in history.
我认为股票这个概念，在历史上被反复提出过多次。
2
The idea is to profit from fleeting changes in the price of a stock.
其理念为在瞬息万变的股票价格中盈利。
3
The school seems to proceed on thefoolish idea that we can delimit a minimum stock of learning in history or geography which we can consider the absolute requisite of an educated man.