The rocker arm pivots around its supporting shaft so that the valve end of the rocker arm is forced downward. This downward movement forces the valve to move downward off its seat so that it opens.是什么意思_The rocker arm pivots around its supporting shaft so that the valve end of the rocker arm is forced downward. This downward movement forces the valve to move downward off its seat so that it opens.在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句