A usually adjustable opening in an optical instrument,such as a camera or a telescope,that limits the amount of light passing through a lens or onto a mirror.是什么意思_A usually adjustable opening in an optical instrument,such as a camera or a telescope,that limits the amount of light passing through a lens or onto a mirror.在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句