短语词组短語parabola mass -spectrograph 拋物線質譜儀mass spectra spectrograph 質譜儀mass -spectrograph velocity-focusing 速度聚焦質譜儀velocity -focusing mass-spectrograph 速度聚焦質譜儀double -focusing mass-spectrograph 雙聚焦質譜儀 返回 mass spectrograph