信息如下：
Selected classification: SITC Rev.4
Selected commodities: 711 (Steam or other vapour-generating boilers, superheated water boilers, and auxiliary plant for use therewith; parts thereof)
Selected reporters: China
Selected years: All
Selected partners: USA
Selected trade flows: Export
结果只能查到2007年之后的信息，是因为我以游客的身份登陆的吗？
求大侠帮助！！！翘首期盼！！