1.Two definitions of“investment”:①In finance，investment means the purchase of a financial product or other item of value with an expectation of favorable future returns.In general terms，investment means the use of money in the hope of making more money.②In business，the purchase by a product of a physical good，such as durable equipment or inventory，in the hope of improving future business.

2.margin n.borrowed money that is used to purchase securities.This practice is referred to as“buying on margin”.借用于购买证券的钱。这种做法被称为“以保证金账户买入”。

3.paper trading n.Using simulated trading to practice buying and selling securities without actual money being involved.While a paper trade can be done by simply keeping track of hypothetical trading positions，it usually involves the use of a stock market simulator that has the look and feel of an actual stock market where budding investors can hone their trading skills.The proliferation of online trading platforms has made it easy to practice paper trading without committing actual capital.Another benefit of a paper trade is that it can be used to test a new investment strategy before putting new money into it.Paper trading may also give novice investors or traders the impression that trading is quite easy，and lull them into a false sense of security.This is because paper trading does not involve putting one's hard-earned money on the line.As a result，basic investment strategies such as buying low and selling high—which are quite difficult to adhere to in real life—appear relatively easy to make while paper trading.The first lesson of paper trading，therefore，is that while it is a great practice tool，it is very different from actual trading with real money.纸上模拟交易；模拟交易；仿真交易。顾名思义，就是在买卖股票、期货、黄金和外汇等证券、金融交易产品时，不进行真金白银的实际操作，而是事先假定自己有一定数量的资金，以此来进行凭空想象的虚拟操作。

4.purchasing power（sometimes retroactively called adjusted for inflation）n.the value of a currency expressed in terms of the amount of goods or services that one unit of money can buy.Purchasing power is important because，all else being equal，inflation decreases the amount of goods or services you'd be able to purchase.Each jurisdiction has its own rules governing margin transactions.In the United States you can purchase up to 50% of securities on margin，so，if you had＄10，000 in a margin account，you'd be able to purchase up to＄20，000 worth of securities.Said another way，you have an extra＄10，000 of purchasing power（buying power）.To measure purchasing power，you'd compare against price index such as CPI（Consumer Price Index消费物价指数）.A simple way to think about purchasing power is to imagine if you made the same salary as your grandfather.Clearly you could survive on much less a few generations ago，however，because of inflation，you'd need a greater salary just to maintain the same quality of living.购买力，为一经济学术语，顾名思义，即是取得收入之后购买货品和服务的能力。它反映该时期全社会市场容量的大小。5.tax liability n.the amount of tax owed；calculated by applying the tax rate to the tax base纳税义务，是指根据宪法和法律规定，公民必须履行的向国家缴纳一定税款的责任。其特点是具有强制性和无偿性，是国家财政收入的重要来源之一。中国的税收主要分为三部分:①对流转额征收的，包括工商税、增值税、盐税、关税、集市交易税和牲畜交易税等。②针对收益额的征税，包括工商所得税、国营企业所得税、中外合资经营企业所得税、外国企业所得税、个人所得税、农业税（自2006年1月1日起，中国全面废除农业税。）③针对财产、行为的征税，包括城市房地产税、契税、烧油特别税、建筑税、屠宰税、车船使用牌照税。中国的税收原则是“取之于民，用之于民”，体现了国家、集体、个人利益的一致性。中国1954年的宪法规定了纳税义务，但1975年、1978年的宪法取消了这个规定，1982年宪法恢复。一切偷税、漏税的行为，都是违反宪法和法律的行为。