【单选题】________with so much trouble,we failed to complete the task on time.
【单选题】The earth around the sun.
【多选题】一对标准安装的渐开线标准直齿圆柱齿轮,下列叙述正确的是_______。
【单选题】一对渐开线标准直齿圆柱齿轮 , 实际中心距 , 下面说法正确的是 ( )。
【单选题】______with so much trouble, we failed to complete the task on time.