Eccentric quarter turn butterfly (or double or triple eccent

Eccentric quarter turn butterfly (or double or triple eccent double or triple Tripe eccentric butterfly valve double or nothing single double triple triple-double什么意思 新概念英语第三册 29课 funny or not 及31课 a lovable eccentric 的错误 turn 加to do or doing? give it up or turn it loose turn a switch on or off Did he turn round or not? Double Flanged Butterfly Valve 是什么