1. the second classroom; practical training besides lecturing in the classroom：第二产业secondary industry | 第二课堂the second classroom; practical training besides lecturing in the classroom | 第二上市secondary listing
2. the second classroom; practical training besides lecturing：第二产业 secondary industry | 第二课堂 the second classroom; practical training besides lecturing | 低谷 all-time low; at a low ebb
3. the second classroom; practical training besides：第二产业 secondary industry | 第二课堂 the second classroom; practical training besides | 第二上市 secondary listing