【单选题】At the beginning of each course, the teacher should give a very ______ explanation of his plan for this course.
【单选题】某三相发电机绕组连接成Y形时线电压为380V,若将它连接成Δ形时,则相电压为( )。
【单选题】项目是不是为完成某一独特的产品、服务或任务所做的一次性努力。
【单选题】David gave us a vivid ________ of his trip to Mount Tai after his return. [ ]
【单选题】When people started questioning his explanation,he had to______ more details. [ ]
【单选题】After his long and complicated explanation, I finally ________ his main point.