GD137/21 SOUTH CHINA SEA GEOLOGICAL SURVEY WORK BY M/V “HAI YANG SHI YOU 708” “HAI YANG SHI YOU 709” AND “NAN HAI 503” IN AREA BOUNDED BY 21-41-48N 116-19-21E，21-41-48N 116-21-05E，21-40-10N 116-21-06E，21-37-07N 116-18-30E，21-36-46N 116-16-50E，21-37-29N 116-16-04E，21-38-30N 116-15-49E AND 21-39-15N 116-16-00E FROM 3 JUL. TO 30 OCT. SIGNAL LIGHTS AND SHAPES WILL BE EXHIBITED ADVISED TO AVOID GUANGDONG MSA CHINA