【单选题】If you had _____ your test paper carefully before handing it in, you would have made fewer mistakes.
【判断题】The stonemason promised to replace the step at a price of 20 pounds.
【单选题】铁和碳的合金,通常叫碳素钢,钢中除铁碳外,主要含有()。
【单选题】It is very ______ of you to take care of the children while their parents are away.
【单选题】金属扣合工艺的扣合键除选用镍铬不锈钢外还可选用______。
【单选题】船政造船经历的三个时期分别是:“木船时期”、“()”、“钢船时期”。
【单选题】发动机异响故障会出现发动机正常运转时所没有的响声,同时会出现发动机振抖、( B )、排气管排烟颜色异常等现象。
B.
运转不稳定、功率下降、燃润料消耗增加、运转无力