再流焊	离合器轴齿轮与副轴齿轮是() ["永久啮合","经常啮合","有时啮合","永不接合"]	对称道岔的导曲线半径是与之同号码的单开道岔导曲线半径的()。 ["A、1倍","B、1.5倍","C、2倍","D、不一定"]	剩余“往返”、“联程”用途票额于开车前()日23:00返回路网“公用”。 ["7","9","10","12"]	键式同步器总成内有()根键弹簧 ["一","二","三","四"]	简述台虎钳的正确使用和维护保养?