Under variable pressure of natural gas,the cracks will be propagated it may lead to break and invalidity.The effect of internal surface cracks are more serious.是什么意思_Under variable pressure of natural gas,the cracks will be propagated it may lead to break and invalidity.The effect of internal surface cracks are more serious.在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句