美国经历了为期十年的极低利率时期，这导致投资者和贷款人通过太高所有类型的资产和进行高风险贷款活动寻找更高的收益率。
The US has experienced a decade of excessively low interest rates, which have caused investors and lenders to seek higher yields by bidding up the prices of all types of assets and making risky loans.