1. 电子商务 electronic commerce

造句练习：在数字时代，电子商务在经济领域扮演着越来越重要的作用。

参考答案：In digital era, electronic commerce plays an increasing role in the field of economy.

2. 投资 investment

造句练习：按照国际惯例，在一个国家教育投资应该占其国民生产总值的4%。

参考答案：In line with international convention, education investment in a country should account for 40 percent of Gross Domestic Product (GDP for short).

3. 购买力 purchasing power

造句练习：经济的发展使国民的购买力大幅提升，从而有更多的钱用于教育、旅游、日常开销等。

参考答案：Economic growth brings citizens greater purchasing power which makes it available for them to cover education, travel，daily expenses and so forth.