解释下述行业对经济周期做出的反应： a．生产耐用品的行业； b．生产储备品的行业； c

．有3年工会工资合同的行业； d．在市场中拥有垄断力量的行业。 Explain the response to the business cycle of an industry a．that produces durable goods． b．that produces storable goods． c．with a three-year union wage contract． d．with monopoly power in the market．