Some people cannot afford to pay their mortgages because their incomes were too low. The banks began to take over the houses from the home buyers who had defaulted on the loan, and then sold them at very low prices, resulting in a step-by-step price fall in the area. This vicious cycle caused a further decline in housing prices. When the housing prices had fallen to a certain extent, more and more home buyers found that their house values became lower than their loans. Thus, more and more people stopped repaying their home mortgages, resulting in a large number of bad debts.
从而有人因为收入过低支付不起房贷，于是银行就开始收回房产，当银行从拖欠贷款的购房者手中收回房产之后，他们会以极低的价格售出，从而导致了该地区的房价一步步下滑，这个过程又引发了房价进一步的下滑，形成了一个恶性循环，当房价下跌到一定的程度之后，越来越多的购房者发现自己的房子价值甚至已经比自己的贷款还低了，于是就有了更多的人停止继续还房贷，又造成了更多的坏账。