单项选择题
A.20~30mmB.30~40mmC.40~50mmD.50~60mm
办公用椅的上身支撑角约为()A.90°B.100°C.110°D.120°
单项选择题办公用椅的上身支撑角约为()
A.90° B.100° C.110° D.120°