【简答题】脉冲强化浸出的方法有气压或液压脉冲、( )、( )和( )等。
【单选题】People _____________ by plane many years ago. [ ]
【判断题】无差异曲线的斜率不变时,无差异曲线呈直线,表示两种商品之间是互补的关系
【简答题】A.travelling men B.men travelling C.travelled men D.men travelled
【判断题】无差异曲线的斜率不变时,无差异曲线呈直线,表明两种商品之间是互补的关系。
【单选题】They travelled to Chicago by ____train..
【判断题】冷却风扇主要由发动机水温开关和冷却风扇控制单元控制其运转及运转时的转速 。( )
【简答题】A. travelled B. was travelling C. had travelled D. used to travel