【判断题】The parallelogram is parallel to the projection plane, and its projection on the projection plane accumulates into a line.
【判断题】When neighboring planes intersect, one should draw the projection of the intersection line
【单选题】搬动梯子时,应( ),并与带电部分保持安全距离。
【简答题】在铰链四杆机构中,能够作 360 ° 回转的连架杆称为 。
【单选题】The projection line which connects frontal projection and profile projection is perpendicular to axis .
【判断题】The projection of a vertical line on the vertical projection plane must accumulate into a point.