Tiān / wén / xué / jiā / tōng / guò / guān / cè / xīng / xì / xuán / zhuǎn / de / sù / dù / tuī / cè / chū / le / àn / wù / zhì / de / cún / zài / 。天文学家通过观测星系旋转的速度推测出了暗物质的存在。Astronomers inferred the existence of dark matter by observing the rotation speed of galaxies.