start knob

例句：

1. 1. The car's engine starts with a simple turn ofthe key.
   只需轻轻转动钥匙，汽车就能启动。
2. 2. The remote control has a startknob on the back.
   遥控器背面有一个启动旋钮。
3. 3. The new app requiresyou to press the start knobbefore starting the program.
   新应用程序需要你按启动旋钮才能开始程序。