【单选题】导线全长620m,算x坐标增量闭合差为0.12m,y坐标增量闭合差为-0.16m,则导线全长相对闭合差为( )。
【简答题】Unfortunately, when I dropped in, Doctor Li _____ for Beijing to join in the fight again SARS, so we only had time for a few words. A. just left B. has just left C. is just leaving...
【判断题】血小板在哺乳动物是无核细胞碎片,在其它脊椎动物是有核梭形血栓细胞。( )