1.human capital 人力资本

例句:Investment in the social sectors is investment in human capital.
对社会部门投资就是对人力资本投资。

2.economic theory 经济理论

例句:Economic theory suggests that the devalued pound will boost the economy.
经济学理论指出贬值的英镑将会促进经济的发展。

3.pay off 偿还

例句:I'll pay off my debt with this check.
我将用这张支票清偿欠债。

4.refers to 涉及

例句:His statement refers to people in general, not to anyone in particular.
他的发言是泛指一般情况，不是针对某一个人的。