screw and double nut

例句：

1. 1.The car's engine needs a new set of screws and double nuts.
   汽车的引擎需要一套新的螺丝和双螺母。
2. 2.He tightened the screws and double nuts before starting the engine.
   他在启动发动机前紧固了螺丝和双螺母。
3. 3.The mechanic replaced the screws and double nuts with new ones.
   机械师用新的螺丝和双螺母替换了原来的。