横过停有机车、车辆的线路时,如何通过较为安全?
参考答案:
应先确认该机车、车辆暂不移动,然后由该机车车辆较远处通过。
After ________in the research for so many years,the scientist succeeded in finding the result at last.
A.buried
B.being buried
C.having buried
D.having been buried
圆柱齿轮减速箱有单级、两级、三级的三种形式。