单项选择题A.expensiveB.artificialC.educationalD.low-cost
单项选择题A.up toB.onC.inD.about
单项选择题A.toolsB.robotsC.machinesD.electronics
单项选择题A.moneyB.discountsC.pricesD.costs
单项选择题A.mechanicalB.standardC.cheapD.small