题型:判断题 My father _____ away for two months. I want to do something special for him when he comes back next week. [ ]A. will be B. has been C. was D. had been 查看答案
题型:判断题 平推流的特征是()。A、进入反应器的新鲜质点与留存在反应器中的质点能瞬间混合B、出口浓度等于进口浓度C、流体物料的浓度和温度在与流动方向垂直的截面上处处相等,不随时间变化D、物料一进入反应器,立即均匀地发散在整个反应器中 查看答案