单词	今古
释义	同ANCIENT
随便看	observational statement observational study observational twilight observation and learning activities observation angle observation angle (of a retroreflector) observation angle [of a retroreflector] observation apparatus observation aviation observation balloon observation battalion observation board observation boat observation buoy system observation car observation check observation circuit observation class rov observation class rov {=ocrov} observation data observation data (o-data) observation date/time # observation deck observation description observation desk